I got a pre-owned Valkyria Chronicles (VC) last week so after enjoying it for an hour - the game crashed. After a couple of hours of troubleshooting and forum surfing, I concluded that the lens of my PS3 got busted :-(
I brought it to a local shop and we have the same conclusion. They replaced the lens for a fee and gave me a 2-week warranty. So this situation forces me to "burn-in" the replacement for the next 2 weeks.
I'll be switching between MGS4 and VC though the latter will get majority time as I'm loving this strategy game.
PS3 games I'm currently thinking of acquiring - Uncharted 2: Among Thieves and NBA 2k10.