It sounds like it could be a problem with one of the cables. Are both sides equally taut and moving freely?

This tends to happen more often with 'stretch' springs then with torsion style, though I have seen it with both.

As mentioned above, check the cables. If indeed it is the cable, then the door will be coming down slanted.
Chances are it's catching on the weather-stripping as it tightens up against it.

Another spot to check is the top hinge.
It's adjustable in most cases and if the bolt is loose, that will also bind as it closes.

Check also the tracks for side to side spacing.
Typically the bottom of the track is set close to position the door. If it's been hit, it may be pinching the door.

Hope something here helps you!