I've never had much luck installing Ubuntu's October releases; Ubuntu 9.10, the Karmic Koala is no exception.
Remember, what Canonical calls a regular release, other vendors would refer to as a testing/development release - preparations for the real deal - what in Debian is known as the Stable release, and what Canonical calls an LTS.
Before I go any further, I'll suggest a quick look at LaserJock's blog post about good/bad Ubuntu releases.