KB93681 Fails to Install

I had this same problem (Windows Vista Home Premium) and MS was of no help whatsoever. I had an update history of KB936181 installing every day for the last two weeks. Thanks to you all for you guidance, especially jaybart and chandler22. I removed the installations of any MSXML 4.0 (I didn't have the Parser version). Once I did that, it automatically reloaded KB936181 overnight on its regular update check. Today it seems fine and thankfully, there's no icon in the system tray telling me to install it again. Thanks to all of you for your help with those of us who "know enough to be dangerous" with our computers!