When something like this happens, it's better to boot with the boot codes "base norestore".
Deleting extensions like that will cause problems if other extensions depend on them - it would be better to remove extensions from onboot.lst.
For the few seconds xmms played did you hear any sound?
Were you using Xvesa, Xfbdev or Xorg-7.7?
I've never, ever managed to crash xmms