I haven't used the actual AIM program in a while, mainly due to the amount of ads they serve. Have you looked at Pidgin or Digsby?
If all you want is AIM with no advertising, the download AIM-Pro at
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That is a recommendation for non-beta Windows.
It seems to me that every iteration of AOL and AIM have all kinds of different problems with Windows7. Even if you think you've installed it correctly and it appears to start and text correctly, you'll suddenly find yourself with incoming IM noises and invisible text.
AOL has a lot of work to do before any of their clients are Windows7-fully functional.
Oh, and if you are using Pidgin with Windows 7-64 bit, go one version down.
2.4.3...