live messenger 8.0.812 crashes

[cypherth]

from the moment i installed live mseenger built 812, when i end a call messenger crashes, and i have to open the task manager and kill the application.
my sharing folder cannot sychronize and with special people such as my girlfriend cannot display her image. i tried to find any possible solution but with no result. includin open/closed firewall, install, uninstall messenger, downgrade, upgrade, patch the program, clean uninstall with specific instrauctions from microsoft help....
i dont want to format the hard disk, does anyone has the same problem?any solution?