It's now happened twice. I think both times I was in an S2000 '06, and I was adjusting one of the gears on the fully-customizable tranny. I was tuning within the expert Seasonal Event at Twin Ring Motegi (FR non-race at 500PP max). The whole tuning sheet was a little touchy and seemed slow to respond to any inputs. Then in the middle of adjusting 4th gear, my system froze forcing me to shut down and restart. Anyone else suffering similar fates? This event (Twin Ring Motegi Seasonal) is my favorite grind-and-tune at the moment.
Possibly just a dirty disc, or might be corrupt game data. I dont know ive never had that issue so that would be my two guesses.
I would say neither of those. I've had the same thing happen to me a handful of times since release. I keep my disc/PS3 impeccably clean and there is nothing wrong with my game data. Not sure what the cause could be, but I am pretty certain its neither of the reasons you have given.
Try this http://www.gran-turismo.com/au/gt6/manual/#!/option/network and see if this helps with your problem.