Happens on Edgy with 2.6.17 kernel too. They are completely random lockups during playback of media files. I think it's got to do something with nvidia driver or xorg.
kern.log just before lockup shows the line: NVRM: Xid (0001:00): 6, PE0000 0cb8 00000000 0000fdf4 867effff 441c1347 -- Random system lockup on video playback https://launchpad.net/bugs/66892 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
