Did some searches on a couple of other forums. Here's the link I found that fixed it:
Mass Storage issues? (Here's the fix) - Discussed in BlackBerry Multimedia forum - PinStack.com - Smartphone Professionals Alliance.
I had unlocked and debranded my phone to get the 2G/3G switching capability. When this became available on AT&T ROM's I rebranded my phone back to AT&T and must have lost the mass storage capability. The file referenced in the attached link fixed the problem.