MSXML 4.0 SP Security Update (KB927978) failed to install problem

had this really annoying and common failure for months, 4, must have had it
attemp to automatically install 100's of times, no fixes here were an good,
the registry hack for permissions somehow just reverted to user, eventually
found on;

http://msmvps.com/blogs/obts/archive.../20/63533.aspx

which describes the problem exactly, and here was the solution;

quote: "Solution! The entire key HotKeyLocalMachine\Software\Classes needed
the SYSTEM account with full control permissions. Once this was changed, the
install completed without issue."

after posting above, i had a thought, live messenger stopped working, unable
to log in, about 4 months ago, so on the off chance i just checked it, and it
is now working, the kids will be so pleased, i did all the updates for it,
checked for info etc. no luck when it suddenly failed, since they have kept
trying desperate to get back in, it could only of be really recently when it
spontaneously started up again, seems like too big a coincidence to me.