A lock-up is one big reason that I gave up on Legend of Spyro: The Eternal Night. Besides the cheap enemies and unforgiving, sparsely spread checkpoints, it froze a lot. I spent a HUGE amount of time going through a level I really did not like. I beat the boss...got a cutscene...and the game froze on the loading screen after the cutscene.

when I reloaded...as was back at the very beginning of that level I friggin' despised. I quit after that and I never played the game again. I turned it in a couple days later as after THAT, I knew I wouldn't be able to get back into it. I had enough.
Though I do think at the time, another reason I lost my patience is because I got Okami at about the same time, and that blew me out of the water.