This from Kelly's Korner: (
http://www.kellys-korner-xp.com)
Go to Start/Run and type in:
msiexec /unregister [click ok]
Then Start/Run and type in:
msiexec /regserver [click ok]
If neither of the above has helped: Go to Start/Run/Regedit and navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSIServer
Does the image path in the right pane correctly point to: (modify drive letter as needed)
C:\Windows\System32\Msiexec.exe /V
If not: boot into safe mode and then go to Start/Run/CMD and type in: msiexec.exe
Once done and while still there type in: msiexec /regserver
Check the image path again, if it is now present, reboot.