Just for information if it can help : if I disable in "User switcher preferences" the "Lock the screen after switching users" (for each user) I get no more the white screen issue.
Gutsy+Nvidia with Compiz enabled.
Just for information if it can help :
if I disable in "User switcher preferences" the "Lock the screen after switching users" (for each user) I get no more the white screen issue.
Gutsy+Nvidia with Compiz enabled.