On my Toshiba T8000 laptop with RH 6.0 and neomagic, the gnome menubar is not properly redrawn after shrinking it (<- or -> buttons on left and right side). The netscape ICON, pager, running apps, and clock are all messed up (double or tripple images). After a few seconds, the bar redraws and all is more or less as it should be. Redraws are worse after using the right menu bar button (->). This could be a Neomagic problem....
Try upgrading to the latest GNOME packages that are available on the updates site. Reopen this bug if you are still having problems after updating.