Ok, having some more info does help is try to make better suggestions for you. Have seen some issues with RoadRunner ISPs before.
That modem is pretty basic and shouldn't need any configuration. I use a SB6121 however I'm on a different cable system. What speeds up and down do you pay for?
Let me ask you this? If you bypass the modem, does AIM work with out disconnecting?
What PC Platform are you using Windows or Mac? What OS version?
Maybe you might be interested in having someone review your routers settings with you. Might help.
Let us know.