Comment 362 for bug 129910

An additional, maybe related culprit, which I am asking other users to verify; maybe it helps to track down what's really going on:

Two Different X-Sessions, the first one created by logging into KDM, second one created by "Switch User" with a different user from the KDE-Menu. The two sessions can be reached by Ctrl-Alt-F7 and Ctrl-Alt-F9.

Almost in 90% percent of the cases switching back from F9 to F7 results in a blank screen with the mouse pointer present and I can see its shape change when hovering over the KDE-Menu, Also, Input is possible by Alt-F2.

Since I have another distribution (Mandriva) sitting on a different partition, it simply works there, so this is definitely an /K)Ubuntu problem. Also, in Mandriva I can use a console with hi-res framebuffer and switch back and forth without problem.