ToolTip Pop Up

I have taskbar locked to the bottom of the screen. When I run the cursor over the items in the tray or quick launch, little pop up windows show up. For example when cursor is over the clock a pop up will give greater details. Every once in a while pop ups are opening under the taskbar and I am able to see just a small portion of the pop up. I have to restart the windows and all is well again for while with pop ups on top. Any ideas how I can correct this or at least get them back over the top of the taskbar without restarting windows would be appreciated.

 

Ratz