AOL 9.0 is known to have a lot of problems (bugs). Besides that, I'm not a fan of AOL. But, I'll tell you how to try to get it installed, anyway.
You should first totally uninstall AOL. To do that, you should use Revo Uninstaller (do not do it from Add/Remove programs):
Revo Uninstaller Freeware - Uninstall Software, Remove Programs, Solve uninstall problems
Use the "Moderate" or the "Advanced" setting when you uninstall it (you'll see what I mean when you run the program). Don't use the "Built-In" or "Safe" settings. When that's done, reboot your computer and try to install AOL 9.0 again.