Some more things...

- I have a motherboard of Sparkle Technoligies. I've downloaded the newest driver from their site, but it still won't work.
- I also removed all other video adapters and monitor adapters but that also has not any influence on that new cart.

I 'm quite sure that it isn't a videocart-driver problem but maybe a hardware problem or a problem with the motherboard.
I bought the cart by a shop on the Web (www.csl-computer.de) and they say that it has to be a problem with the motherboard, in the past they had a lot of that kind of problems, and it was always a motherboard problem (to old bios etc.).

Maybe someone else has a totaly new idea, please write it down here.