That happened to me a while ago.
Providing you have AOL 9.0, and Voyager 100/105 I will asume you have.
The easiest way is to go Start>All Programs>AOL>AOL System Information. Then go to 'WAOL' Then click 'Data Folder' Then click on C_AOL 9.0>ukpppoecswitch(Or the closest to it) Then click Voyager 100 (Is that your modem?) You will see an app called 'doctor100' Use that to uninstall the modem, it will clean out all the crap they leave behind. (Thats what AOL told me anyway!) Reboot and install the new drivers.
Sorry its a bit of a mission, but it is needed.
That should do the trick. If not post back and i'll have another look.