Solution #1

double-click file "ProcPerfCounter_fix.reg" to run it on your PC.  This will attempt to fix a value in the Windows Registry.  
After fixing the registry, try running the Desktop Assistant.  If the problem is not fixed, proceed to solution #2.

Solution #2

If step 1 did not fix the problem and if you are running Windows XP with Service Pack 2, then two of the Windows system files may be corrupt.

Locate the files, perfc009.dat and perfh009.dat in C:\Windows\System32\.  

Make copies of these two original files and save them somewhere else on your computer as backups. 

Put the two files (perfc009.dat and perfh009.dat) into the C:\Windows\System32\ directory.  Select yes, if asked to overwrite.