Computer Locking Up

[anaxcrosswords]

My PC (running XP) is getting a bit old but it's been extremely reliable.
However, it did something 2 months ago which it's never done before - that is, it completely locked up. No cursor movement, no response to mouse or keyboard. All I could do was hard reboot, after which it was fine. And it's happened twice again since then.
On all 3 occasions I've just been working on 'normal' stuff. A couple of pieces of crossword software, an anagram app, and Word, with Firefox open in the background. I've been working like that for at least 5 years with no problems.
Any suggestions as to what might be happening to make the system freeze like this?

[Mosaic]

I had a similar experience with a little netbook two weeks ago. I found this link very useful ans clear: http://www.malwareexperts.com/how-to-remove-win32downloader-gen/

This showed that my netbook seemed to have copped a virus that jiggered the registry. It kind of works now but is still not right - I want to re-install the OS but...its a netbook....no disk....ooo-er.

[Wak]

I downloaded some updates for my XP a couple of weeks ago and they messed my comp but not as bad as yours sounds. To cure it I had to restore back to just before the updates and it's been fine ever since.
Any chance you could restore back to, in your case, a couple of months??
They are stopping updates next year anyway so I don't think loosing a few updates will matter. You would think that they could have had it working first class by now without all these extra updates, wouldn't you?

[anaxcrosswords]

Unfortunately, running eventvwr is throwing up several errors which point to a potential hardware failure, i.e. HD giving up. Looks like I'm on borrowed time!

[galeck1947]

Time to move on and upgrade to Windows 7 or 8.1 . You should be thinking seriously doing this as the deadline to support cut off gets closer. Windows 7 computers are getting very hard to get now.