Freezing PC

I want to scream!

I have done a system restore, run through virus checkers (AVG/Windows defender) - done a diagnostic memory test (no issues found). Also defrag'ed and run ccleaner.

Sometimes we can go a few hours - other times - it is happening every 2-5 mins, I start it up and it freezes - have done safe mode and safe mode with networking.

It is an Acer thing running Windows 7. I use Chrome as my browser.

Any ideas?

Does it freeze up if your not doing anything? I had my old win 95 system start doing that to me once years ago and it was just after I got a new card put in,turned out with me the so called "new" card was screwed and was the cause of the freezing.

It could be overheating but I doubt that, my thoughts are most probably your graphics card has decieded to start to pack up! have you got another card you can use just to see? that's on the thought that it is a tower system! if it's a laptop then your up the creak as they are more a built in chip than a card! but if you got a tower and a spare card then swop em out and see what happens! if it stops then there's the culprit!

How is it freezing up? As owner of a new PC (Christmas pressy) with Windows 7, OH recently installed Windows Security Essentials (or whatever it's called) onto my PC for me, and literally the minute it was installed, my PC started freezing up (always on the browser, but whether this was co-incidence or not I'm not sure - I surf a lot!). Ctrl-Alt-Delete wouldn't work, right-click and close, nothing, just had to wait 5 minutes for it to unfreeze. Funnily enough, his PC had been doing it since he installed Security Essentials but it wasn't until then that he made the connection. Sure enough, we removed it from both PCs and neither have had a problem since.
We couldn't find much googling the issue other than perhaps an issue with Security Essentials and a certain graphics card (that we both have in our PCs), but worth considering if you have Security Essentials installed.

My local computer show does a diagnostic for under £20. Why not ask your local shop if they do one?

Go and buy a copy of Linux Format from your nearest supermarket and run your PC from the supplied DVD for a while. If it runs OK, this points to a Windoze problem. If it keeps freezing still, it's a hardware problem.

If it's the latter, I'd suggest, as a starting point, ensuring all the air vents are clear & you can hear fan(s) running from time to time. If possible, take the lid off and check any cooling components are nice and clean.