Evidently rendering Messenger dead is not a problem or priority.
I tried closing all current applications, rebooted your computer, closed any open apps, goto run type %temp%, delete everything in that folder (temporary internet folders), empty recycle bin, then run the Plus setup as administrator .
I tried reinstalling Windows Live 2011.
I tried "repairing" Windows Live 2011.
I removed Messenger+ & rebooted.
Windows Live ran perfectly!
I reinstalled Messenger+ as "administrator" & Windows Live crashed running the sign in page!