I have, on a tandem trailer behind a 75series cruiser 
. Short version - Went to stockton, before even getting onto the actaul beach, driving out of lavis lane in 4H my car hits a pothole and goes clunk, 4x4Stick is jammed tight (unmovable) and in drivetrain is stuck in neutral 
Towed to servo, left for 2 nights, sunday we pick up tandem and trailer it to sydney... decide to just fiddle with it before taking to mechanics, and we fixed it so I wasted $165 on a trailer for nuthing, AND didnt get to drive on dunes
Oh well, I know for next time ay, exhaust ALL bush mechanic options before towing 
Longer, slightly funnay version, I went with a few people who never REALLY been camping, and havent really been 4x4ing before. Got there late (7:30ish), and on the track to beach, one of ours gets bogged cause he's towing a water tank (~850L for hot showers etc
), the GQ snatches him. We go 100m, theres sum other wally's stuck. Watch and wait for ~30 mins, they unstuck, we keep going, 200m and a Prado is stuck towing bikes, followed by a Mazda Tribute with NO low range and a smokin clutch cause the guy is trying to un-bog himself in high range 
- this delay of course meant the 4B towing the water got stuck cause they lost momentem, so had to snatch them too.So about an hour to get the poor buggers out, then its dark and we finally get onto dunes and cant find the beach
, drive around aimlesly for nearly an hour till we find the way back and decide to go to anna bay, then my car breaks, then we pile into the remaining cars (~12:30am by now), went all the way up to Anna bay on the black top, then ALL the way back down on the beach to the shipwreck ~3hrs all up (75series got stuck twice in this period, ended up dumping all the water TWICE, ones on lavis, filled up, then dumped again at anna bay end 
) got to camp ~3am, ate, drank, fell asleep.Theres a few other details but this is already long,
to Kane, "The Rocky" from this forum for saving the day and bringing us water, and looking at the manual ended up helping even if we did fix it back at sydney So for the tech, has anyone else had this unusual thing happen to them (jamm in Neutral from 4H) and what could have caused it? It feels really good now, but not sure if its a ticking timebomb waiting to happen again... and then not get fixed so easy
Before we pulled it out, it was hard to change from 4h-2h sometimes, now it's smooth as 