I've been dealing with a freezing PC for over one month. Please allow me to elaborate on this issue. After the system has loaded Windows 7, there's a chance of it freezing. Usually within 15 minutes of booting. Sometimes it doesn't even give me any time to check it out and it freezes once it loads the desktop. But if it doesn't freeze at the beginning it wont freeze throughout the entire session(MEANING IT CAN RUN FOR 20+ hours without any problems). But it takes a few hard boots to get it to work.
At first I figured that it was software related, so I booted into safemode. Freezes, but less frequently. Next reformatted my hard drive and re-installed a fresh version of windows to make sure it wasn't because of some boot files. Still freezes, so i disabled all the startup files, such as antivirus, still freezing.
I tested my memory several times with "memtest". Tested my hard drives. Tested CPU. And removed tested my video card and switched over to my onboard graphics.
Here's what i found out:
-If i use my video card It gives me a regular freeze with the last thing that was on my desktop ( mouse can't move nothing moves).
Sounds really interesting, perhaps it might be your graphics related issues.. Since you found 2 swollen capacitors there might be a chance that its creating those problems.. based on your system i see that it is quite old ( not in a mean way )