First I want to thank everyone for the replies, unfortunately the problem still hasn't been solved. Now I must say that I'm not an expert in these things, but I'm quite sure I followed all advises correctly.
@karelj: Yes, that's exactly the same problem, 'Glad' to see I'm not the only one!
@Crossg: I don't get an 'uncheck ide drivers' option when I want to remove the nvidea drivers. It just uninstalls the latest graphic card drivers. All bios settings are set to 'autodetect', but how do I know if it uses the default Ms drivers??, also: How can I check for Mobo bios updates?