Re: can i fold to this check raise on the flop?
 

Against an unknown I don't see any problems taking a WA/WB attitude after the flop raise. I expect to see an A here a lot, but I want to know what he's limping UTG. And if he did hit the monster and plays like this then that is certainly some useful information for later hands.

Re: can i fold to this check raise on the flop?
 

haha....nah, you didn't lose to AJo [img]/images/graemlins/smile.gif[/img] he either put you on the hand you had (in which case he screwed up and should have check raised the turn, as noted by Grease), or he has the flush draw and was betting on the come. don't know if I agree with your bet on the flop though...you either had the best hand or you were drawing to a 2-outer. No need to bet there. flush draw will stick around, and no other non-A hand will beat you.