if you meant me that is
.
To the original poster:
Does GarageBand ever hang on the initializing window? Or does it load normally before quitting on you, like you said? I know that the latest version of GB fixed the problem I, and many other GB users, had with the initializing window, which would appear for at least 30 seconds or so before it actually opened a file or greeted you with the new project menu. Seeing that your Mac is up-to-date, I do not think we will have to worry about that.
There is always the possibility that there are some corrupted preferences files. You may not want to delete them, but GB should make new files in the event that they are gone. Those can be found in the Library somewhere... I think it is under GarageBand in Application Support, but they do not show up in either of the libraries on my old iMac here...
Normally I would check permissions for something like this as well, but if you've already done that, then it might not do any good. Does Console report anything odd when you attempt to launch GarageBand? Console is in the Utilities folder and may report on some problems if it finds any. Try looking there.
-BMF