If you receive the subject error while visiting Windows Update:
01. Start / Run / regsvr32 iuctl.dll /u / OK to un-register the library.
02. Use Start / Search to search for Files and Folders. Type iuengine.dll, iuctl.dll into the file search box.
03. Delete all occurrences of these two files, deleting the ones in %SystemRoot%\System32 last.
04. Re-visit Windows Update.