Go to Start/Run and type in:

regsvr32 /i shell32

Note: The spacing is important.

If that doesn't correct the issue use this automated edit:

Search Opens When Double Clicking a Folder or Drive (Line 18)
http://www.kellys-korner-xp.com/xp_tweaks.htm

To use the VBS File: Download .vbs file and save it to your hard drive (you may want to right click and use Save
Target As). Double-click the vbs file. You will be prompted when the script is done.

Tufenuf