I started experiencing kernel panics (requiring a full reboot) while playing back media files on VLC. This only began happening after updating to Mac OS X 10.5.6. So for now, I'm using Perian 1.3.3 within QuickTime Player and that's working okay. XBMC and Boxee both seem to be functioning fine. I posted this issue at VLC's forums but I thought I'd post here too.