this from kellys-korner. if you procede with the registry edits make sure you back up the registry first and understand how to revert back to the backup if there is a problem.
Question: Why does Windows XP Style change to Windows Classic Style?
This has to do with a Policy setting made either via gpedit.msc or manually via the registry. The side effects are that Windows and Buttons are greyed out under Desktop Properties/Appearance and the check box under System Properties/Advanced/
Performance/Settings that reads: Use visual styles on windows and buttons, does not remain checked. This edit corrects that behavior. Download and apply either one on line 214, they are the same edit.
Windows/Buttons Greyed Out under Appearance and/or Windows XP Style Changes to Windows Classic (Line 214) http://www.kellys-korner-xp.com/xp_tweaks.htm
1. Right click the My Computer icon/Properties/Advanced/Performance/Settings. Verify that: Use visual styles on windows
and buttons is checked.
2. Windows Explorer/Tools/Folder Options/View. User Common Tasks in Folders.
3. Right click the Desktop/Properties/Appearance. Windows and Buttons choose: Windows XP style.
4. Start/Administrative Tools/Services. Scroll down to Themes and verify that the service is started.