Transmission Locking up! Help!

Hey everyone, I need some help. I have a 2004 Pontiac Aztek, 99k, very well cared for. A few days ago I started the car and it sounded like rocks tumbling around right next to my left front driver wheel. Backed the car up, opened the hood, noise was gone and drove it fine to work- about half a mile. Left work, backed it up and kinda was bumpy. I drove maybe 8 miles and it was fine, the last mile or so it started hesitating and not wanting to shift, came to a dead stop across the street from my house. Towed to a dealer, told me the transmission is locked, the fluid is burnt and I need a new transmission-3800 for trans and labor. I towed it home, and the tow driver started it and drove it off the truck! It drove about 70 feet or so and locked up. Restarted it and drove it about another 30. Does this sound like a transmission problem or something else? They didn't even change the fluid, I am just not convinced.....

Please help me!

Diagnosing problems like this can be extremely difficult over the internet, however if the fluid is burnt and the trans is acting the way you say it is, then it is very possible the trans is toast. Putting new fluid in would be a waste at that point, so they actually saved you money if that is the case.

Thank you for your reply. There is a mobile mechanic in town that looks at cars for free, he said it is possibly a solenoid. fingers crossed, it has been a really great car :-(