Ubuntu Linux 8.04 (Hardy Heron)

Using VLC or Totem, playing a video file hangs my entire system. The audio still plays, and I can still use the mouse, but my keyboard does not work, and I can't kill X.

This is annoying, seeing as I could play video files two nights ago. The problem seemingly arose after I updated to the new kernel (which was a necessary update, said Ubuntu)

alex@alex-laptop:~$ uname -a
Linux alex-laptop 2.6.24-18-rt #1 SMP PREEMPT RT Wed May 28 23:38:58 UTC 2008 i686 GNU/Linux

Does anyone have any suggestions or a solution for my problem?

This is why I love the Linux community. I didn't even post my problem at another forum, and in less than two weeks, a new kernel was released (2.6.24-19), and my problem was fixed.