Sounds like something wasn't done right. Here's what I would do, because something is corrupt.
Back up all music files, etc. to your computer.
Go to this link for the package that I put together (It's nothing fancy, just the exact bits from Samsung / AT&T for UCLB3 Gingerbread with root added.):
Reinstall the package. After you follow ALL of the instructions there, including the ones for wiping user data and cache, let the phone boot.
Go to settings / sd card and phone storage / Format USB storage. Let it format.
If you've kept music files on the external sd card, format both the internal sd and the external sd. Be sure that you've saved anything you want to keep to your computer, because this will wipe these partitions clean.
After that, go to settings / privacy / factory data reset / reset phone and reset the phone to factory defaults.
Put your music and other files back on the phone.