Hi again and thanks for the replies so far....
harrystainer: I have tried to re-install them and also tried a driver which where a little bit older, because it could be a new error in that driver or some beta-driver shit, but without luck, but I?ll have a go at the driver thing again.
Doc Jones: I just thought "naaaah" with your reply, because I have had the system up and running several times without any hardware change and with no problems, but then I remembered that I actually got a new MIDI interface (Miditerminal M4U by ESI) and then I thought "yeah, maybe thats the thing! It is powered by the USB...Could probably take some power". So you actually mean my PSU in the computer is too small? (I think its 300W or so)
Can I check this someway or is it just change it and see if its better?
Is there an onboard PSU consumption meter or so? an application?
If I turned it off when experiencing the problem I guess I could easily see if it was the thing causing the problem....
Juho L: this wouldn?t be the issue because it?s when I am using it, not when those 10, 20 or 60 minutes have passed....It is stress-related
Jasedee: "Get a real computer, Muawhahahaha"? Hope that it just was a joke....I have used several computers and set them up for friends and professionals, and none of them are flawless, so I dont know what you would mean with "a real computer"? a new computer?
My system is really put specially together (also costed the same as 2 standard computers back then!) and I keep high maintenance and runs only applications and services which it needs so I have a computer that is better running than the most 2500+!! (except for this issue

)
It is mostly for sequencing MIDI stuff to hardware synth and so, so it should be fast enough!
But tell me something about that PSU stuff?
Psypher