We all forget something. That its possible to forget to lock manualy the hubs. Happened to me once, a few days after the big snow threre were some snow patches on my job's parking. A car had stuck and i had to manoever the rig so that I coul winch it out. I engaged 4wd I manouvered the car on the snow were the other was stuck ( about 5-8 inches) thought that it slided a bit but I sail it was icy and then I found that I had forgot to lock the hubs... stupid of me but it happend.
and in case you wonder I winched him out with 1st on four high ( Yes I have locked the hubs <img src="/forums/images/graemlins/lol.gif" alt="" />)