Thanx for the fast reply
Everything seems to be working fine. Linux boots, it starts KDE (although here the screen is already scrambled) and all the applications seem to work as well. For example, I can start applications like xterm or emacs, however, they appear on screen all messed up (lines running all over the place). Therefore it is also impossible to start hardware configuration tools, because the intefaces are scrambled up and I can read a word.
During booting there is a line saying "no screenmap" or something like that (excuse me for not having the exact wordings, I don't have my laptop with me at this particular moment, I'll sent a more detailed description in a couple of hours).