Repair of WindowsXP Theme?

I have lost the WindowsXP Theme settings in the Start menu,the Task bar and the Caption buttons. Seems like they are all now in Windows Classic Theme.This just happened overnight!
The "Display Properties" Themes tab is set to WindowsXP; but. in the Appearance Tab, the Windows and Buttons options window offers only Windows Classic. Is there some file or folder available (maybe on the Installation CD?) that might be used to overwrite and restore the XP theme? (Systen Restore did not fix the problem.)
I have kept current with the updates including SP1 and would prefer not to have to reinstall the complete WindowsXP to reair this annoyance.
Thanks,
Norm

 

Try this:

Control Panel/Folder Options/General tab/Restore defaults/apply/ok....not sure if you'll have to reboot or not.

 

By the way, I don't know why you switched to the Windows Classic look but the reason I did was because the Windows XP theme results in CPU usage spiking to 100% when any folder is opened....with subsequent slowdown in performance.

To test for this Ctrl+Alt+Delete to bring up Windows Task Manager. Select Performance Tab and pay attention to the CPU Usage meter. Open My Computer, select any drive, even a CD drive, and right click and hold, leaving the menu drawn. Watch your CPU usage climb to 100% and stay there as long as you keep the menu open! Change to windows classic folders and repeat experiment. Spike disappears.

I've just switched back to the Windows XP theme to see if phenomonon is still there and it is, so its back to the Classic look for me.