Are you talking about white frames around the borders of the units and that kind of thing? If so, that's not an nUI bug, it's a bug in the BLizzard graphics drivers and there's no way I can fix that... there's a FAQ on it here:
http://www.wowinterface.com/forums/s...ad.php?t=25715
If you're talking about something else, please post a screen shot so I can see what you're referring to.