I've noticed this also on my system (Ubuntu Natty, running Ubuntu Classic no effects without Compiz). I have a Dell 1420 laptop with an Intel video 'card' ("Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller" according to Hardinfo). I notice it in the classic Gnome panels a lot, where parts of the panels became darkened. I have attached some screenshots showing different instances of it happening (the corruption is the dark parts; the missing white parts are editing on my part).
** Attachment added: "Screenshot-top-panel-corruption.png" https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/781983/+attachment/2130473/+files/Screenshot-top-panel-corruption.png -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/781983 Title: Screen becomes corrupted under normal usage _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp