So, last night I'd done virtually every side quest and main quest, killed 9 of the ten dragons, and was questing in the Hissing Wastes. I got all the way to the tomb with a Dragon sleeping outside of it. I knew it was there cos a friend warned me. I went and attacked the dragon, and for the first three quearters of the fight it went fantastically. Then the game bugged, and suddenly my characters could not move unless i took control of them and made them jump over invisible obstacles (they could still fight though, provided they were in range).
I still managed to kill the tenth and final High Dragon but, maybe due to the weird glitch, I didn't get the Dragon Slayer achievement. I also could not loot anything, and had to save and reload to sort both bugs out.
