Only guessing here, but I think it is time to check your diff.

With one shaft out, anytime you had rear wheel spin, TOD would have sent power to the front diff.
The side gears would have just let the diff internals spin, possibly causing premature wear to the diff.
Perhaps a combination of things allowed the good shaft to pull one end out of the socket. After that it would have thrown itself out fairly quickly.

Would have made a lot of noise though - do you drive with head banging music turned up so that half the city can hear it??

PK