I re-read your post a few times but I'm afraid I still don't quite understand what your saying.

Are the hubs working or not? Or is this issue purely with your handbrake?

The Auto hubs aren't the greatest bit of gear around. They are prone to locking while driving in 2H for no reason other than they wear out as far as i know. It used to happen to my GU a lot. You would be driving a long and all of a sudden you could hear the front hub(s) starting to try and lock.

To disengage 4wd, you are supposed to first change it into 2H from 4L, then reverse (in 2H) up about 2 meters to disengage the Auto Hubs. If this doesn't happen, the hubs would possibly be still locked in on 2H (2 wheel drive).

As for your handbrake, no idea. Best off getting a mechanic to check it out perhaps.