Took me a bit to see what you were talking about. If it happens every time then I would try turning on software OpenGL and see if it changes. If so, then look at video card and driver. You might also try unpinning the menus to see if that changes anything. If it does it might be a clue.
I was able to fix this. Reset to default.
There was a problem that has been fixed in SolidWorks 2011 where this behavior would occur if you have a regular toolbar docked to the right of the CommandManager and also have the text descriptions turned off on the CommandManager.
I hope this helps,
Thanks for the replies but I'm not sure what was the problem. I just hit the restore to default on the Part and Assembly Template and all is well now.