Talk App-What's making it initiate suddenly?

[Letty]

I've had my Droid for a couple years, but suddenly it is sending me messages that individuals want to chat with me. I traced it to an app I haven't used called "Talk". It signals that someone wants to chat and I have the option to ignore. It also tells me who's available, etc. But I don't want it to be active. It seems to be gleaning from my email list because sometimes it's just an email not a name. How do I STOP it! I've gone to Talk settings and unchecked everything but still getting notified. The people don't even know that I am being notified, so they aren't asking for me. Thanks for any help!