I just ran into this and managed to solve it, but it was a pain. Here's my situation:
- New iMac 27 inch
- Used Migration Assistant to transfer all user accounts, user files, and applications off of an older (late 2006) iMac that had been upgraded to Snow Leopard and iLife '09
When trying to install the full set of Apple Loops and Software Instruments, I got the infamous "run Software Update but nothing ever downloads" problem. After doing a lot of looking on these boards and elsewhere, I decided to uninstall GarageBand '11 and reinstall. Uninstalling GarageBand '11 is a pain too; here's what I did:
- Deleted GarageBand from the Applications folder
- Deleted the /Library/Application Support/GarageBand folder
- Deleted the /Library/Audio/Apple Loops/Apple/Apple Loops for GarageBand folder
- Deleted anything related to GarageBand in /Library/Receipts
- And everything in ~/Library/Application Support/GarageBand (this is optional I think)
I then reinstalled GarageBand from the second install disk that came with my new computer, fired up GarageBand, and downloaded the recommended update. Finally, I opened up a new Loops project; in the Loops Browser, selected one of the missing loops; got the "run Software Update now or later" dialog, and said "Later"; quit GarageBand. Finally, I opened Software Update, and lo and behold! the near-mythical GarageBand Loops and SW Instruments update was there, all 1.2 GB of it!
I wish that Apple would come out with a patch for this, but in the meantime, if you're situation is similar to mine (upgraded GarageBand '11), you might try the deinstall / reinstall route and see if it works...