I've been having a problem with intermittent stuttering in video and audio playback since upgrading to Maverick (it also happened when I briefly installed Lucid). It started out as the odd skip every 20 minutes or so but now it can happen 5 or 6 times in 10 minutes when watching a film.
reformatting and clean installing
using a half-dozen players
installing every codec I could think of (only after the normal ones wouldn't help)
diangosing my 3 hard drives (the problem occurs on them all and they're not in a RAID setup)
changing then changing back my video drivers
disabling pulseaudio and ubuntuone-sync (these were not installed in my previous, working setup)
looking at every relevant log file (mplayer, smplayer, demsg...) I know of
running ubuntu's testing utilities
I'm out of ideas. Going back to Jaunty is the only solution I'm pretty sure will work but it's not exactly ideal. It will be a few months at least before I'm able to install a completely new distro.