AIM - shutting down

We can log onto AIM with no problem, but as soon as someone tries to instant message me or I try to instant message someone else, the program shuts down. It is an issue for me, because my kids and husband are in different places all over the country, and this is one of the ways we stay connected!!! Any suggestions would be greatly appreciated.

BTW -- I have run ad-aware, and yes some spy ware was removed, I have run a virus scan. I am sure there is still something in the machine, but I am where??

Thanks in advance.