Hmm about 10 years ago (i was a young fella) my brother was towing his hilux on a trailer down to collie for a competition weekend. The tow car, a VS commodore was chuggin along fine when the trailer started to sway. They treid all the usual thigs, speed up, slow down but nothing worked. It all got too much, and the trailer rolled. The tow car survived, with 5 guys needing new undies, but the trailer and the hilux were a write off.

After the insuarnce company investigated, they found that the trailer had severly worn bearings. The axles were shifting back and forward in the brackets casuing the whole axles to steer the trailer. Lucky for my brother, the trailer was hired, and the hire company had to pay.
Lucky for my brother, they had tied the hilux down well enough so that it was in fact one with the trailer. he also lost all his tools from the tray. i remember going back to the crash site a week later with a metal detector to try and find the rest of his tools. We only recoverd about half, but he still has the same tool chest, but its somewhat bent these days...