Okay, 15 attempts, 1 succes. No idea why it worked then though. But that setting didn't work, and I haven't been able to boot into the forced mode again. And I don't think that actually happened. It seemed to have booted up in 1280x1024 (the default) that time, while all other times failed.. Strange..
Oh, I use a Packard Hell 14" 4:3 display that does display 1280x1024 8x8x8 no problem, as that's what the CD boots up with as well..
So why does the CD boot every time into the desktop, and the harddisk boot doesn't remains a mystery..