Windows: Installing Service pack 2 on Windows 2003 Server fails with Access denied.

If you tried to install SP2 on Windows 2003 you might have run into a problem with an Access Denied error. Check the file: c:\windows\updspapi.log. You will see that there is a problem deleting a registry key:

#-086 Deleting registry value “HKLM\Software\Microsoft\Windows NT\CurrentVersion\SvcHost\wugroup”
#E033 Error 5: Access is denied.

The problem is that the administrators group on has read only access to this Key.

Resolution:
In regedit go to HKLM\Software\Microsoft\Windows NT\CurrentVersion\
Right click on SvcHost and change the administrators group to Full Control

Fix By: C. Boessen – Write up: Timothy Conrad