Office communicator 2005 Sign IN problem

HI,
I’m using microsoft office communicator 2005 ver.1.0.559
Whenever I try to sign in ,It gives a error that my time & date in incorrect.SO go to control panel>date & time then check it.There is no problem with my system time.
I’ve tried to change the time zone and also reinstalled the messenger but it didn’t work…
plz help me out.