This problem is caused by a bug in Windows that causes the taskbar
tool-tips to lose their "topmost" window style and be covered up by
the taskbar.
Check out this web site for more information and a permanent fix:
http://www.acquaviva.us/tooltipmanager
Tool Tip Manager was written specifically to fix this annoying problem
by processing taskbar window messages and resetting the "topmost"
window style for tool-tips as needed, automatically. This program also
allows you to customize the appearance of the task bar tool tips (font
& color) and set the automatic hide timer value.
Regards,
Nick Acquaviva