Installed a fresh Windows Vista Business SP2 on an HP DC7900 a couple days ago and since then I haven’t been able to install Windows updates.
I’ve installed/reinstalled the Windows Update Agent 3 (with
/wuforce), re-registered Windows Updates DLL files, and have also done an
sfc /scannow. None of these actions have resolved the issue.
Google leads me to all types of solutions, hacks, workarounds, thoughts, and so on. Nothing worked.
I downloaded WSUS Offline Update tool and worked around this issue. After applying those updates, I could successfully Check/Install new updates.