Hi Hilbert!
At the moment I get 'fatal errors' 3 times a week at least so I can feel the pain. Nothing left to do than switching off the system than...
(You noticed it once during MSN, last week; I was gone in a flash)
I've had so many problems with Windows in the past.
But when I came to installing Windows several times a week I replaced the harddisk and that seemed to work.
It can be a hardware problem. What Window version are you using and what system do you have?
A few months ago I litterly 'blew up' my system: I just switched it on and saw a flash comming out the pc and it smelled like fire... Nothing worked anymore.
The powertransformer inside was gone, as well as my cd-writer, disk station and keyboard. Some other parts survived. Funny enough: the fuses that would prevent this from happening was still OK...
I suspect an intergalactic conspiracy against Microsoft... Perhaps aliens are trying to tell us something  :-) 
When I got some money 'left' (or when I grow up) I'm gonna buy an Apple, because they don't seem to have as much problems as the "Gates machines" we all wanted to have. I see them actually in every proffesional business were people are working with graphics and photo's. But they say it's a whole different world... so I hesitate a bit.
Paul