One problem related to seat belt has been reported for the 1999 Toyota Avalon. The most recently reported issues are listed below.
Serious problem with front passenger seat belt: I had shoulder surgery and had to put the shoulder strap across my back so that it wouldn't cross my bad shoulder. So, we get to our destination and I start to get out of the car and forget I still have the seatbelt on. My wife gets back in and releases it, and I go to get out and the damned thing won't pull out/loose. Since the idiot thing thinks it's protecting me, I push a little of it back into the slot assuming it will then release. Nooooo! it just gets tighter. We start the car to see if that releases it. Nooooo! every time I move it just gets tighter. A freaking boa constrictor could take lessons from this thing. After it's abundantly clear that the seatbelt has won, and I'm bound up like a thanksgiving turkey, we get the scissors and cut it loose. The Toyota engineers really blew this design. Several folks have said they've had the same problem, especially with kids in car seats. Actually, this problem could be kind of dangerous if you're in an accident.