can't sign in (ver. 6.0)

I cant sign in , there is always a message for me saying there is a new versio(6.2) and instruted me to download. When its done downloading, error occurs ."error in code "1601" "and instructed me to Go to msn messengerservice. I decided to just remove it f
rom my add/remove.. again there is a message saying "Windows installer service could not be accesed, this occurs if you are running windows in safe mode, or if windows installer is not correctly installed, Contact your support personnel assistance. Ple .
help me I dont know what to do now I need the newest version to be installed.