With 290.x and 295.x drivers, after relogon (!), I get black menus in KDM and black & transparent windows in KDE4 and Gnome.
In 285.x and earlier series it was OK.
Steps to reproduce:
1) start KDM
4) KDM menus are broken with black areas at the bottom (see image )
5) login again
6) windows/menus are broken: some are transparent, some are black (see image )
Logout. Restart X server from the KDM menu - after restart KDM menus work fine again. Login - windows/menus work too... All until next logout...
nVidia GeForce 8600GT
Debian GNU/Linux 7.0 Wheezy (testing) 32-bit
KDE tested: 4.6.4, 4.7.2, 4.7.4