2000 Blazer front wheel lock up

Hi everyone,
I have a 2000 4 dr blazer 4wd. I''m having a problem with the front wheels locking up while backing up on a sharp turn. It happens more when the wheels are cranked all the way to the right. The right wheel will actually lock right up. Sometimes when this happens it will automatically switch from 2wd to 4 high, and a couple of times even 4 low. It''s starting to bite a little in forward now on sharp turns, so I wanna get it fixed. I am replacing the front hubs this week, so I figured when I have it apart, I can go in and hopefully fix the problem. Just wondering if I can be pointed in the right direction. I bought new tie rods and upper/lower ball joints, so I''ll probably do them too while I''m in there. (not sure when they were last replaced and the blazer has over 280,000 km''s!!)
Thanks in advance.