Comp freeze, "serious error" recovery on reboot

Over the last month or so my computer has been randomly freezing in the middle of perfectly normal activities that had previously caused no trouble at all (eg. web browsing, word processing). When it freezes, I usually get a screen that resembles this:

http://farm4.static.flickr.com/3405/3231977569_d097f01ebf_o.jpg

Note that the cursor (in this snapshot it's a box because of the program I was using) remains recognizable and intact in front of the messed up display.

Sometimes, but not always, the screen goes to black almost immediately after doing this.

When the computer freezes, Ctrl-Alt-Del doesn't work (of course), and I have to manually reboot using the switch on the comp tower.

Upon reentering Windows I get a "Windows has recovered from a serious error" display that looks like this:

http://farm4.static.flickr.com/3091/3231977763_83bdc6c83b_o.jpg

On occasion, when I reenter Windows, the display does the same messed-up thing as in the first photo, but Windows is still functional. I can reboot the computer using the Start menu, but only because I know where to click (I could also do it using the keyboard if I could remember the series of keystrokes).

Sometimes when I go to boot up the fans will whirr like it's going to go, but then never cut out and the load never progresses (in an ordinary problem-free boot, the fans whirr for about 6 seconds and then go quiet and the computer proceeds with the rest of the load).

From the poking around I've done I'm gathering that these Serious Errors are often hardware problems. I've checked my hardware manager and have found nothing in error state (not that that necessarily means much). I've also tried fiddling with the RAM (I have three sticks - one 1 gb and two 256 mb), leaving the pair of smaller ones in and taking the large single out, and removing the pair and leaving the single - as far as I could tell, neither configuration made any difference, but perhaps I just didn't give it a long enough trial.

Recently the boot-up issue hasn't been happening as much, but the messed-up screens have been happening more often. On the chance that it's hard-drive related I've backed up my personal files to another drive. However, the computer is only 2.5 years old, so I wasn't expecting hardware failures for another couple years at least, based on the fact that the comp this one replaced was 8 years old when it bit the dust.

Any ideas on what to do? This is getting tiresome. Thanks in advance!

 

Thanks for the tips, PeteC. As it turned out, I posted that in the evening, and the next morning when I went to boot up, the computer wouldn't start. Wouldn't even give me a whirr when I pressed the button (at least in the past it would start up and the fans would go but it wouldn't boot).

I went through the troubleshooting steps of seeing where the problem lay. I had to pirate a power supply from another computer to even get the thing to power up, but even with everything else disconnected - drives, RAM, non-vital peripherals - it still wouldn't boot into BIOS.

Soooo it's off to buy a new computer. I did discover, however, that the hard drive itself appears to be just fine - I put it into another tower and it boots up and runs with no problem. At least that's a relief!

Thanks again for your suggestions - wish I'd had a chance to actually try them out! I think the computer knew I'd given up on it - they always seem to be aware of these things.