LR3 error - "a response was not received in time"

Question

I have been using LR for a couple of years now and have uploaded many web galleries to my website.  Recently, however, it is just not happening for me.
I have been trying for 3 weeks to upload 3 web galleries in LR3 - they range in size from 200 - 300 pics per gallery.
The error message I get is "a response was not received in time".
I was using the trial version of LR3 before buying but was told they could not help me unless I'd bought the software.  VERY helpful and not exactly great PR!!  As I was desperate with waiting clients I bought the upgrade anyway.  That was a week ago.
I have spent 1.5 hours on the phone to the US LR support and as long with UK support (US was way better).
I have had return calls from LR and a promise to hear back from the engineers as the problem was escalated.  That was nearly a week ago and I've not heard a word.
I am using a brand new iMac bought on 22 July and haven't done anything other than try to process and upload these 3 galleries so have huge amounts of memory available.
I have unlimited web space.
I have uninstalled and reinstalled LR twice.
My 8 year old pc can upload the galleries fine (although soooo slowly as it is inadequate for this type of work), so there is no connection problem.
As a work around I exported the galleries to the desktop and uploaded using 5 different FTP programmes.  Filezilla seems to work best, but although the gallery uploads, not all the pictures appear properly - normally 10 - 20 pics are a problem.  Even though they appear to have uploaded, only the thumbnail shows, not the large image.  It is not the pics as if I reload a gallery it will be different pics that fail to show correctly each time - totally random.
I have been able to upload a gallery through LR of between 1 and 5 pics, but no more than 5 (proving the settings are fine), until today.
Today I managed to upload over 400 pics using an html gallery. 
Next I tried uploading 50 in a flash gallery and this also worked, so I tried to upload 1 of my 3 complete galleries.
The first attempt resulted in an "unknown error message" - believe it or not I was quite hopeful as at least it was a different error message.
The second attempt resulting in "a file was truncated during upload"  Never seen that one before.
The third attempt resulted in my now familiar error message of "a response was not received in time"
Desperate for help please.

Answer 1

JaneNeedsHelp7 wrote:
I don't understand why it works fine with a PC - have tested with 3, 2 of which are seriously old - but not with my brand new iMac.  I thought that getting whiz bang machine I'd have fewer hassles. 
In my experience, it is the wizz bang machines which always seem to have the problems! I must admit to sticking with my desktop (a Windows machine) rather than my Laptop (a MAC) when doing FTP transfers using LR as certainly with LR 2 the FTP in LR on the MAC did seem to have some hiccups. Perhaps using a separate FTP to upload the site is the best solution for the time being although the other problems you report don't seem to directly relate to the FTP. There were some more detailed postings in the past from MAC users on this issue and some about the BIN file problem on windows servers, so a search may help.