Can't network Mac with W7 Ultimate 64 bit (but W7Pro32 and WXP work)

Question

Hi all,
I posted a long (probably too long) issue recently but despite nearly 200 people viewing it, no-one offered a solution. So I am re-posting a shorter, clearer statement here but below I also enclose the long full diagnostic information (at the bottom).
At home we have 4 computers: a Macbook Pro with OS X 10.7, a Windows XP desktop machine, a Windows 7 Professional 32-bit laptop, and a Windows 7 Ultimate 64-bit workstation. As a result of my extensive experimentation and testing I found that:
- Networking and sharing drives between the Macbook and the XP machine worked fine in both directions
- Ditto for the Windows 7 Professional 32-bit laptop - everything "just worked" exactly as it should
- However the Windows 7 Ultimate 64-bit machine simply would not work from the Mac to the PC (I was however able to access the PC from the Mac)
- All PCs were of course able to inter-operate in both directions across the network with each other
My conclusion therefore is that the Mac is set up and working correctly, there are no connectivity problems, and almost certainly this is an issue relating either to 64-bit W7 (versus 32-bit) or it's an issue relating to "Ultimate" versus "Professional" (or both). I have not 'fiddled' with anything, the only setting changes made which could be considered low-level were the 'secpol' change on the W7x64 machine which I read in many posts might solve the issue (it didn't).
I am not a technical expert although I have some ancient history in the field. I just want it to work. Everything I read tells me that it should - now Windows and Mac both use SMB, etc etc. But it doesnt.
Absolutely desperate to get this solved quickly now. I would even happily have paid someone, but finding an expert in Switzerland who can come to the house, speak English fluently plus (of course) be fluent in Windows 7 Ultimate x64 and Mac... it's proved to be a test too far. So if anyone out there can help... thank you in advance.
Alastair
ORIGINAL DIAGNOSTIC DETAILS
CONCLUSIONS
There appears to be a fundamental compatibility problem between Mac OS X and Windows 7 Ultimate 64 bit.
The problem actually appears to have a degree of randomness / instability about it (see below when, during diagnostics, the workstation actually disappeared, then reappeared!).
I can only presume this issue relates in some way to the “enhancements” either related to Ultimate versus Professional, or to 64-bit versus 32-bit variants.
At the moment there is only one solution I am confident would work, which is to revert my workstation to 32-bit… however this is not an option for me as it would render around 21GB of RAM unusable and remove the whole raison-d’etre for purchasing a powerful workstation in the first place.
I am therefore stuck and in need of help!
PRECONDITIONS
In all cases I am using connectivity between three different PCs and a Macbook Pro 2.53GHz Intel Core Duo, 4GB RAM, Mac OS X running version 10.7 (Lion). BTW I know Lion is new but it was exactly the same with 10.6.
I have three PCs: an XP Pro machine, a W7 Pro 32bit machine and a W7 Ult 64bit machine.
All three PCs are running the same antivirus and firewall (Norton Internet Security 2011), this was left ON for all tests on all machines.
I have already been through all the myriad of advise on this subject: as you can see from the below, file sharing etc has all been enabled. The “secpol” changes etc have also been made on the W7 Ult 64bit machine only (but these were only made because it didn’t work without the changes and everyone seemed to think this was needed).
All my Windows computers are configured to workgroup “WILF” and also set this Workgroup name on the Mac in the WINS settings dialogue. No homegroup exists on the network.
No other “tinkering” has taken place. Although I have some tech skills, I am just a bloke who wants to use his computers, not a computer genius. As such the Tosh laptop is pretty much fresh out of the box, the Mac has nothing non-standard and the only setting change is the WINS setting for the Workgroup name. The workstation is a little over a year old so but I have not poked around with anything deep inside it, so if there is anything wrong it should be superficial – the kind of thing a basic user could have changed by mistake and can easily be changed back.
DIAGNOSTIC TESTS
Connecting between Macbook and old Windows XP machine (XP Pro 2002 SP3):
-        Open ‘Finder’ on Mac, PC immediately visible under ‘Shared’.
-        From Mac: Single click on PC icon indicated “Connecting” then “Connect as Guest”, opens a list of all shared and public folders. Am able to copy files from Mac to PC, am able to copy files from PC to Mac.
-        From PC: Opening “My Network Places” and clicking on “View Workgroup Computers” shows all my networked computers including the Mac, double-clicking the Macbook icon opens a list of all shared and public folders. Am able to copy files from Mac to PC, am able to copy files from PC to Mac.
-        In short: this appears to work as it should.
Connecting between Macbook and new Windows 7 machine (W7 Pro 32-bit 2009 edition, Tosh laptop w/ Intel Core i7 M620 @ 2.67GHz, 4GB RAM):
-        Open ‘Finder’ on Mac, PC immediately visible under ‘Shared’.
-        From Mac: Single click on PC icon indicated “Connecting” then “Connect as Guest”, opens a list of all shared and public folders. Am able to copy files from Mac to PC, am able to copy files from PC to Mac.
-        From PC: Opening “Windows Explorer” and single-clicking on “Network” shows all my networked computers including the Mac. This time I decided to try logging into the Mac drives as me, rather than as a guest:
Double-clicking the Mac icon opens up the ID / Password dialogue box.
Inputting my correct username and password for the Mac immediately opened up all the folders on the Mac I have access to (the shared / public folders but also the folders for my login account on the Mac).
Am able to copy files from Mac to PC, am able to copy files from PC to Mac.
-        In short: this appears to work as it should.
Connecting between Macbook and fairly new Windows 7 workstation (W7 Ultimate 64-bit  2009 edition SP1, Supermicro workstation w/ 2 x Intel Xeon W5590 @ 3.33GHz, 24GB  RAM):
-        Open ‘Finder’ on Mac, PC WAS INITALLY  immediately visible under ‘Shared’… however while carrying out the testing for the XP machine and the laptop, it has disappeared! The other two machines remain visible.
STOP PRESS: It reappeared… for how long, is anyone’s guess…
-        From Mac: A single click on PC icon almost instantaneously indicates “Connection Failed”. Repeated attempts produce the exact same result. To verify the basics some elementary diagnostics:
Mac IP address 192.168.0.11 can be successfully pinged from the PC.
PC IP address 192.168.0.3 can be successfully pinged from the Mac.
From PC entering comment “ping MACBOOKPRO-598A” (the latter being the computer name of my Macbook) works successfully i.e. name resolved OK, no packet loss, 1ms round trip.
From Mac unable to run the reciprocal ping test for EITHER PC since I don’t know what to put into Ping to allow it to resolve the computer names.
However I note that all 3 Windows machines remain visible in the Finder, only the two which work (the XP machine and the W7 32bit laptop) have the “Eject” symbol next to them and they are still the only two which work both ways without problem.
In the Finder window after clicking on the PC icon in the left column, I get another instance of this icon in the next column with “Connect As” underneath and presently “Connection Failed”. If I click on “Connect As” I receive the error “There was a problem connecting to the server ‘alastair-ws’ (which is the PC name of the workstation).
Finally if I use the GO -> Connect to Server option in Finder, using SMB://alastair-ws I receive the same error as above. I get EXACTLY the same error if I use the IP address of the workstation 192.168.0.3 as above.
-        From PC: Opening “Windows Explorer” and single-clicking on “Network” shows all my networked computers including the Mac. Again I decided to try logging into the Mac drives as me, rather than as a guest:
Double-clicking the Mac icon opens up the ID / Password dialogue box.
Inputting my correct username and password for the Mac immediately opened up all the folders on the Mac I have access to (the shared / public folders but also the folders for my login account on the Mac).
Am able to copy files from Mac to PC, although naturally not the other way around.
-        Therefore the PC-to-Mac seems to work OK, but the Mac-to-PC does not no matter what I try, although the IP is visible and it’s clear the connectivity exists (or Mac copy onto PC would also not work).
[END]

Answer 1

You can give this a try on your Ultimate machine.  While these are said to be for Vista, I used it on my Win 7 machine just fine and it fixed the problems I was having.  Hope it works for you.
The problem is that Vista, by default, will only use NTLMv2 for authentication, which is not supported by Mac OS X's Windows Sharing service.
The other problem is the Minimum Session Security for NTVLM SSP based Clients.
To get around this:
1.     In Vista, open the Control Panel
2.     Switch to "Classic" view
3.     Double-click Administration Tools
4.     Double-click Local Security Policy
5.     Or Secpol.msc
6.     Expand "Local Policies" and select "Security Options"
7.     Alternate : Type secpol.msc to get editor up then
8.     Locate "Network Security: LAN Manager Authentication Level" in the list and double-click it.
9.     Change the setting from "Send NTMLv2 response only" to "Send LM & NTLM - use NTLMv2 session if negotiated"
10.     Network Security: Minimum session security for NTLM SSP Based (including secure RPC) Clients
11.     Change the setting from "require 128 bit" to unchecked (No Minimum)
12.     Click OK
the real difference between vista and windows 7 procedure is 10 and 11