Windows XP Desktop Problem - Blank desktop

Start > Run, type in  'regedit'  (without the quotes) in the search box.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon.

In Winlogon, on the right side, there should be a value called "Shell".

Double click this value.  

Make sure only 'Explorer.exe' is the value of Shell, if anything else is there, simply delete it and leave 'Explorer.exe'. 

Close out the window and restart....