maybe the shortcut is broken i dont see why but try going to "C:\Program Files\AIM6\aim6.exe" or reinstall it or restart your computer or use trillian =]
Maybe something in the registeries? Do you know anything about regs? If so.. you can always go and delete all of it and reinstall again..
If you cant get it fix go to the source, to the installation directory. And run it from there. If you cant find the install dir, search it, with windows find.
i'm using that but i like some of the features in 6.0 and i want to try it out i just find it kind of weird that it wont work on my computer