I've had my 04 4.4i for a total of 4 days and I've got the dreaded Trans Failsafe error now.

I was headed home from a short drive and when I stopped at a light, the dash lit up with ABS BRAKE and 4x4 lights. Like a moron, rather than drive the 4 blocks to home, I decided I'd restart it and see if they cleared.

Shut her down and she wouldn't start again. Just click-click-click.

I let her sit for a couple minutes and was able to get her restarted again.
Now the trans failsafe is still on.

I'm hoping it's just a bad battery - car was sitting at the dealer for about 6 weeks before I bought it and it was 20 degrees this afternoon.

Since I've got a warranty, I'd like to take it back where I purchased it... is it a REALLY BAD IDEA to drive 20 miles in failsafe mode?

If it's just the battery and I replace it, will the error go away (assuming there's nothing else wrong) or does it need to be cleared with one of the diagnostic/coding programs?

TIA