Re: getting back default windows themes???
Do you have like WindowBlinds software or anything like it that you're using? If so, deselect any option to "Run at startup" or similar within the programs option window. It's better just to uninstall it.
If that doesn't apply, try restoring the XP theme by opening up Services. Click on Start/Run/Type: services.msc and click OK. Scroll down and double click Themes. Set to Automatic under Startup type and then click the Start button. When Themes starts, close Services. Another thing you can try is to open System Properties. Right click My Computer/Properties/Advanced tab. Under Performance, go to Settings button/Visual Effects tab. Select, Use Visual Styles On Windows And Buttons/Apply and then click OK to finish.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?