When using Windows XP that has been upgraded to SP3, Windows update will begin to fail to install ANY updates. It will run, download, initialize, then fail. If this problem begins immediately after updating to SP3. What the root cause of the issue is, is that wups2.dll has become unregistered. This file is described as the "Windows update Client Proxy Stub 2", and I have no idea what that means. The fix is to stop the WU agent, re-register the DLLs involved in Windows update and restart the agent.
As an administrator, run these commands from the command line:
net stop wuauservThen Windows update should actually finish some updates.
regsvr32 /s wuapi.dll
regsvr32 /s wuaueng1.dll
regsvr32 /s wuaueng.dll
regsvr32 /s wucltui.dll
regsvr32 /s wups2.dll (this is the real culprit)
regsvr32 /s wups.dll
regsvr32 /s wuweb.dll
net start wuauserv
Another issue seen with installations from a slipstreamed XP SP3 CD is that the installer will fail to update the web client itself, claiming certain DLLs to be in use. This is rare but it does happen.
The solution here is to simply delete the files it complains about, this is usually wuapi.dll, wups.dll, and wups2.dll...found in C:\Windows\system32\.
This message is brought to you by RIT ITS CSS Desktop Support Operations. ;)
Side note: more updates coming soon, just getting busy working and doing battle with some new computer hardware.