DISABLE WINDOWS MESSENGER POP UPS

RE: WIN XP. I HAVE A COMP. THAT KEEPS GETTING WINDOWS MESSENGER POP UPS (UNSOLICITED). I HAVE DISABLED THE SOFTWARE (I THOUGHT) THROUGH THE GROUP POLICIES PROCESS, BOTH AT STARTUP AND UNABLE TO RUN…BUT THE POP UPS DO NOT STOP. IS THERE ANOTHER WAYTO TURN IT OFF? OR IS THERE A WAY TO FIND OUT (AND STOP) IF THERE IS SOMEONE WITH REMOTE ACCESS/CONTROL OF THIS VIA SOME SORT OF PLANTED SOFTWARE, ETC.