If you think it's the mouse then try a different mouse, or even booting without a mouse at all just to see if you can boot. But OErjan is correct, most of these strange booting problems turn out to be improperly made discs and the most common problem is a disc that was burnt at high speed. Such discs often seem to work fine on some systems but not on others. Sometimes people don't even realize they have a bad disc and think it's working, but it turns out that Knoppix is much slower than it should be. I don't like it, I think if a drive claims to be able to burn at 48x then the burn it makes at 48x should be just as good as the burn it makes at 4x, but that is just not what is happening in the real world. It is likely that if you don't know the history of your disc that it was created at high speed and a slow speed burn may save you an awful lot of time and effort tracking down strange mystery problems (even if you have other hardware issues on that system).