Jack it up at each wheel and see if it is locked up. Maybe you are onto something with the brakes locking up. The front wheels should spin easily and with the back wheels, have it in neutral, or have both wheels off the ground and test.

__________________
05 SL600 75K
87 MB 560SL 119K
87 MB 300D 180K
83 MB 240D 110K
64 1/2 Mustang
74 Monte Carlo 32K
75 Fiat 124 Spyder
16 Equinox
15 2500HD Silverado