Shortly after installing the Micrsoft game Halo on my system (not sure if there's a connection), the message "You have no contacts in your address book. Please add a contact" started popping up every five seconds (literally) on my screen. Even after deleting Messenger from my computer, I still get a Messenger-related pop-up ("Messenger has encountered a problem and needs to close. Sorry for the inconvenience") every two minutes or so. I can't get rid of it, and it seems to be affecting other elements of my system (e.g. can no longer play music videos or songs on AOL). Don't know if it's software, hardware, virus or what! Any suggestions appreciated.