Issues with Rock Band DLC

Has anyone experienced issues with DLC since updating Rock Band and exporting tracks? Last night, two of us tried playing some DLC and we noticed 2 things:

1. When selecting songs, the on-disc songs would play samples in the selection screen, but none of the DLC would play any sound.
2. After selecting a DLC song to play, at the LOADING screen, we’d get an error message along the lines of “your session has been restarted, press continue and try again”.

I tried a few hours later, just by myself and the DLC worked. So, is something wrong after the update/export?

UPDATE:  According to this post in the Rock Band forums, (http://www.rockband.com/forums/showthread.php?t=62661&highlight=DLC+error&page=4) changing your Gamertag corrupts the Digital Rights Management (DRM) that Microsoft uses on Xbox 360 DLC, to protect against piracy.  That could be my issue, since I changed my Gamertag image two days ago to McCain.  Grrr..the Republicans got me again!

There’s a DRM reset utility available at (http://www.xbox.com/en-US/support/systemuse/xbox360/licensemigration/)  which I am going to check out today.  I’ll be back with an update.  If you know anything else, please share.