Adobe Acrobat 9.0 Pro crashes at start up: Runtime Error-please help

Question

I have Adobe CS4 installed on my Windows 7 PC. In addition, I have Adobe Reader XI and InDesign 6 installed. If I remember correctly, after I installed Adobe Reader XI, I uninstalled the version of the Reader which came with CS4.
So here’s my problem: When I try to download a PDF that has been sent to me in an email or open one that already exists on my computer, this happens:
Runtime Error!
Program: C…
The application has requested the Runtime to terminate it in an unusual way.
When I click OK, I get this:
Adobe Acrobat 9.0 has stopped working.
If I try to Adobe Acrobat 9.0 Pro from my start menu, the same thing happens.
This makes no sense to me because
I don’t have the knowledge to figure this out. I have no idea what Runtime is.
Prior to a computer meltdown a couple of months ago and a complete reinstallation of everything, these very same programs all worked just fine.
I don’t understand why, when I try to open an emailed PDF, they don’t automatically open in Adobe Reader XI rather than Adobe Acrobat. Isn’t the general idea that people be able to open and view sent PDFs which they have been sent, which is what the Reader is for, and not usually edit them, which is what Adobe Acrobat is for?
If, instead of trying to open the emailed PDFs, I save them to my computer, I can launch Adobe Reader XI and open them from within that program without any problem. That’s OK if I just need to view the PDF, but I need to be able to edit PDFs too, so I must get Adobe Acrobat 9.0 to work.
Would reinstalling Adobe Acrobat 9.0 Pro help? Is there a way to reinstall that program only from the installation disks or would have to reinstall CS4 entirely?
I cannot open Adobe Acrobat 9.0 at all, so any solutions which must be done with the program open are not possible.
I would really appreciate some help.

Answer 1

SOLVED!
Resetting Internet Explorer didn't work, Reinstalling Acrobat 9.0 Pro didn't work, but changing a registry key did.
Here's where I found the solution:
Microsoft Visual C++ Runtime Library error opening PDF files - Microsoft Community
Here is the relevant post, but before you try it, read my note below:
Hi,
This is known issue with Acrobat for several versions now, Adobe's current fix is just to update their software: http://kb2.adobe.com/cps/404/kb404597.html
The problem is with the application data being misdirected.
"The affected user has a redirected Application Data folder and as a result the network path containing the Application Data uses a UNC path that begins with \\. This UNC path causes Acrobat 9.0 or Adobe Reader 9.0 to incorrectly parse the Application Data path and give the error message."
A potential Solution would be to go into the registry. Left Click type "regedit" and right click and run the program with "run as administrator". Go to Hkey_Current_User\Software\Microsoft\Windows\Current Version\Explorer\User Shell Folders and make sure see where "AppData" is pointing. If it is pointing to "%UserProfile%/Application Data" change it to point to "%UserProfile%/AppData/Roaming".
BUT, be careful about one thing: This poster seems to have accidentally used forward slashes when he should have use back slashes. Look at the very last line of his post where he advises "If it is pointing to "%UserProfile%/Application Data" change it to point to "%UserProfile%/AppData/Roaming". You'll find, or at least I did, that this key has a back slash, not a forward slash, so changing what I found: "%UserProfile%\Application Data" to "%UserProfile%\AppData\Roaming" worked and now Acrobat 9.0 works fine.