Not here, just to check mine out when I got it.  I left it running for 3 days straight, and it worked fine.  I have also turned it on and off many times without an issue.

Good Luck

Bruce

No problems with the power here either.

cheers

- Hans

That is definately not "normal" behavior.

But before you return it, disconnect everything from the inputs and outputs (including SD card, etc) and try it again.  Also make sure you are plugged directly into the wall ... no regulators, spike protection, etc.  Also you should try it in two locations just to be certain.  If you have a way to measure the wall voltage that would also be a good idea.  I would expect results like you are saying if the voltage drops too much.