The only time I have experienced a similar issue is with huge folders (thousands of files and folders). It hasn't actually locked up, but it took a very long time to load the directory. Not sure if this is similar to what happens to you or not. Are indexing and/or disk compression in use on your system? Flaky or bad memory can cause these kinds of issues as well.
I know you said you have scanned for viruses, trojans and other malware, but trust me on this.
Download the AVG Rescue CD and boot from it and run a full scan. Even though you swear you aren't infected, I think the results will surprise you, and you'll discover something that your currently installed anti-virus missed. I think this happens because when you are in Windows scanning the drive, it is mounted to the Windows OS, whereas running off the CD loads an OS off the CD, then mounts the windows volume for scanning.
In my experience, running a virus scan this way has found many times viruses that were unnoticed by Windows installed anti-virus programs. This is especially true if the anti-virus program doesn't receive updates or is out-of-date.
AVG - Rescue CD | PC Rescue and Repair Toolkit
If freezing still happens it could be another issue all together. You stated that if you reload it runs fine until such point where it starts acting up again. This could be from software or drivers that you are installing. Let's face it, there are some issues with drivers and the 64-bit OS, it sucks, but it's especially true for older devices, and they can cause all sorts of problems that can be hard to trace.
In troubleshooting that after a re-load (if that's what you end up doing again), I'd load software and drivers, one at a time, using the system in between each install to test stability. If you install something and suddenly you're system starts acting unstable you know you have found a link.
The more software that gets installed, the more unstable Windows can become. It's always been that way. Third party tool bars can be responsible for instability issues as well.
I've outlined potential areas to look at in diagnosing your issue, hopefully something will fall into place for you. Good luck!
I know you said you have scanned for viruses, trojans and other malware, but trust me on this.
Download the AVG Rescue CD and boot from it and run a full scan. Even though you swear you aren't infected, I think the results will surprise you, and you'll discover something that your currently installed anti-virus missed. I think this happens because when you are in Windows scanning the drive, it is mounted to the Windows OS, whereas running off the CD loads an OS off the CD, then mounts the windows volume for scanning.
In my experience, running a virus scan this way has found many times viruses that were unnoticed by Windows installed anti-virus programs. This is especially true if the anti-virus program doesn't receive updates or is out-of-date.
AVG - Rescue CD | PC Rescue and Repair Toolkit
If freezing still happens it could be another issue all together. You stated that if you reload it runs fine until such point where it starts acting up again. This could be from software or drivers that you are installing. Let's face it, there are some issues with drivers and the 64-bit OS, it sucks, but it's especially true for older devices, and they can cause all sorts of problems that can be hard to trace.
In troubleshooting that after a re-load (if that's what you end up doing again), I'd load software and drivers, one at a time, using the system in between each install to test stability. If you install something and suddenly you're system starts acting unstable you know you have found a link.
The more software that gets installed, the more unstable Windows can become. It's always been that way. Third party tool bars can be responsible for instability issues as well.
I've outlined potential areas to look at in diagnosing your issue, hopefully something will fall into place for you. Good luck!
