Fritz, try keeping your problem in 1 thread instead of spreading them in different threads.
Back to your problem. I highly doubt that it's a problem with your memory. Disabling the cache of your processor will slow your computer down to unworkable speed.
As I mentioned in earlier posts. Did you send that system crash error report to Microsoft's website and did you look at the analysis of it? Most of the times you can find exactly what caused the problem.
In your previous post you said it was a file from you modem driver. Can you download a newer version of it?
Try updating your bios too.
If it still gives problems bring your computer back to the store and demand another modem.
If the memory was the problem, he would be having issues with or without the modem.