Random freezing for 3-5 seconds, but inconsistent. Help!

Hi everyone. Brand new to these forums because of a very nagging issue that has been occurring only recently.

In a nutshell, my entire computer randomly decides to lock up. Meaning, everything freezes - I can't use my mouse, I can't alt+ctrl+del, nothing. I might be surfing the net on Firefox (which is most of my computer usage) or it could happen as I'm sitting looking at the desktop. Usually these freezes will last for a maximum of about five seconds or so, and then everything is fine again, but sometimes the freeze doesn't disappear. I am then forced to do a hard shutdown of my computer. Now, I could have the computer on for several hours, spend about three hours actually in front of it, and have two "soft" lockups (meaning it bounces back to normal after a few seconds) in that time. Or it could go for 4 hours without an issue. It's extremely random, is what I'm trying to say.

I already tried a memory test (everything was A-OK) and yesterday I ran a CHKDSK - everything's OK. I made absolutely sure that my graphics card driver was 100% up to date - it is. UPDATE: I just checked my Event Viewer, and it just updated with the chkdsk log - even though I ran it last night. I have attached a screen cap, maybe you can see something I missed?

I really don't know what this could possibly be otherwise. Overheating potentially? Never had an issue with it before. I really hope you guys can help me out with this, the absolute randomness of the issue is killing me!

Thanks sooooo much.

-Mike

Just a quick addition - I just tried shutting down the computer, and it just lingered. My monitor was black, as in it did not even have a visual connection. Yet I could definitely hear the hard drive working. I wonder if the freeze happened as it was shutting down. I was forced to do a hard shutdown in this case.

Hey, I haven't tried SFC yet. I'll try that next later this evening. I'll post results. Thanks!

If I'm reading the CHKDSK results correctly...
...it says that Windows found problems with the file system.

I would do as the results suggest, run CHKDSK /F

Then repeat CHKDSK again and hope for a clean bill of health.

After a clean CHKDSK, you can move onto the SFC scan.