There is a problem with any upgrade you did. I had the same issue. It also had popping and buzzing in iTunes. It crashed and fried my hard drive. The only way to get systems to function is to do a clean install of all the upgrades. There is a new "patched" version, 10.2 of Garageband that works in the new protocols. It will export at volume and sound way better. You will have to pay 5 bucks for it now .It will also have very few loops and zero software instruments. You will have to re-load any that you want. I add all the Ben Boldt volumes. Backup anything you want in your library and re-install. I could never get the old Garageband to output at volume doing anything. It works fabulous on the new drive. I hope they clean up Garageband to the old functionality. So far, with little tests, it is okay.