Enable oneiric-proposed or wait 1-2 days for the new compiz release to land in Ubuntu 12.10. It fixes, beneath others, two major NVidia regressions.
I have that compiz version, but it is the same. Like I sad, I had that bug in beta and rc stage of 12.04 development, and then with first update after final release, it was fixed.
That's actually one of the reasons I moved to KDE. XBMC was terrible in Unity. Unity's performance became pretty unbearable, as did XBMC's UI. With KWin it's not so bad.