I have had this issue with two computer in the past.
I had an HP Pavilion TX1000 for a while and had the issue on the Vista OS.
Now I have an IBM Thinkpad T43 with Windows 7 32-bit installed and it has been fantastic up until just today.
I've looked through a lot of documentation on this...
ati radeon
computer troubleshooting
desktop environment
email client
gaming performance
graphics driver
hp pavilion
ibm thinkpad
input lag
minimize restore
software glitch
system performance
taskbar issues
technical support
user experience
vista os
visual artifacts
windowflickeringwindows 7
windows explorer