Computer freezing about 20 minutes after restart

[Silentio]

My Laptop recently started freezing around 20 minutes after turning on. The only thing I can do is restart it again. I thought it might be a virus so I ran an avast scan, it didn't detect anything. Then I also did a malewarebytes scan, it detected four infected files, removed them, restarted, scanned again, and the problem still persisted. I did CHKDSK few times, but it didn't find any problems and didn't help at all. I also have another issue, not sure if it's related,but my security update for .NET framework has been failing. Error code 643. It's been failing for almost a month now, and the freezing problem only started yesterday. so I don't think it is related and I don't really care much about that problem if its not related.
I am running windows Vista SP2 intel pentium dual CPU T3400 @ 2.16GHz 2 GB ram 32 bit OS
What happens exactly is that the program I am using stops responding (like firefox) and anything i click also stops responding. alt tab and ctr alt del stop working and eventually i cant move my mouse. The most I waited was 30 mins, nothing happened.
Any help would be appreciated
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And now it won't turn on. Worst part all of my restore points just disappeared, so I can only do a restore to a factory state.
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I did some testing using a driver CD, and it said error code 0F00:1332
Msg: DISK_0 - Block 6251638: Interrupt Request(IRQ) not sent in time.
When asked if i want to continue I said yes and now it's stuck...

 

[Tmagic650]

Sounds like the laptop is over heating...

"I also have another issue, not sure if it's related,but my security update for .NET framework has been failing"...

Check the shutdown button for a small shield symbol when the .NET Framework update fails. You may just have to shutdown the laptop. DO NOT restart. Start the laptop and run Windows Update from the All Programs area once more once you get the laptop up again. Perform the restore to factory state

 

[Silentio]

I would rather want to avoid the restore to the factory state.
Since at first you said it sounds like an overheating problem i'll let it cooldown for a bit and try to turn it on again, but i guess if that won't work i'll just do the restore.

 

[Tmagic650]

If you can get the laptop up and running, save any important pictures and data to a flash drive or DVD and do the factory restore. If the restore is successful, the laptop will be like it was when you turned it on for the first time... If the laptop is 3 or 4 years old the restore might not function anyway, because of program and update changes over those years...

 

[Silentio]

Well.. I managed to turn it on and save the most important data and I did the restore. It doesn't have any more problems with freezing, however it is actually unusually slow, especially when playing games and websites with a lot of flash applications, which it did not have a problem with before. I upgraded my graphic driver, but it didn't help.