Windows 7 freezes on desktop after startup

Hi, I hope somone out there can help. I've been looking through the forums for a while and I haven't found a solution to my problem.

First of all I'm running Windows 7 Pro 64 bit on an i5 system.

I powered on my PC and it gave me a warning about the machine not being shut down properly. I started windows normally and once I reached the desktop Windows freezes, I can still move the cursor but I can't click on anything. Pressing Ctrl alt Del only causes a black screen to appear and I am forced to reset the machine.

Unfortunately I haven't set up any system restore points. I tried running a memory diagnostic with the Windows 7 CD but to no avail. Serching for problems using the Windows 7 disk turns up nothing aswell. I started windows in safe mode and disabled all programs at startup. After rebooting in normal mode the same thing happened, it freezes just as before.

I installed Windows 7 on a different hard drive partition and it works fine so I'm pretty sure it's not a hardware issue.

Can anyone tell me what I can do to troubleshoot this problem? How do I go about testing which program may be causing the problem? Is there anyway I can try and repair windows files?

I would be really grateful for any help. Thanks in advance.

Specifically, boot into Repair CD or Install DVD Repair console to run Startup Repair repeatedly. Startup Repair

Report back what it finds in the results link.

Thanks for the advise.

I ran the Startup repair several times; each time it doesn't find any problems.
I'm currently running another Windows Memory Diagnostic, I'll report back with the results.

Doing a standard Standard Windows Memory Diagnostic doesn't turn up anything.
I'm currently doing a second extended Memory Diagnostic, both of which have frozen at 21% omplete.

I tried to do a clean boot, I disabled all services except the Windows ones but I still experienced the same problem.

I did a clean boot where I disabled all Windows services and it's working.

I guess all that's left now is to try and find which service is causing the trouble.

If I find out which one is causing the trouble what should I do to solve it?