ghosts when using additional monitor

[ateles]

I have been noticing this annoying behavior when unplugging my PowerBook from a flat screen Samsung SyncMaster monitor: When the screen of the PB comes back it has this little ghost image (like if you would take the very edge of a button or a window). The image sits on top of everything and restartng the finder does not get rid of it. I have tried also changing the resolution and frequency of the display with no luck. If I plug back in the Samsung monitor, the ghost will move there. The only way I've been able to get rid of it is to logout and back in (which is kind of annoying). Anybody experienced this problem?? Any ideas?

Thanks

ateles