Maybe you should...then again maybe you shouldn't. I'd sit him down and be frank with him, "Honey, what's in those folders that you don't want me to see?" If he doesn't feel comfortable telling you, my guess is that it's definitely something he knows that you don't approve of. Good Luck and Hope this helped! :)
I keep all of my files secret, it's not to hide it, and of someone asks I'll show them. I just do it because I don't like the thought of my family creeping through my stuff. I don't have anything to hide.
I say no. He probably stores his porn links, downloaded videos/games, and pictures there. It's perfectly fine. Guys watch porn. So do many girls. He's probably embarrassed by it, so he's hiding them. If you're too worried, just confront him about it. But don't get too worried.
Yes time to worry. Let him know a person with nothing to hide hides nothing;) tell him how his hiding effects you and if there is no trust the relationship dies slow and painfully for both of you. Sorry you are dealing with it;(
Yes, I'd be concerned especially since it sounds as if he's not being truthful about the folder; saying he can't access them. I'd let him know that it's breaking trust having these secrets & if it's porn then that's fine (if it IS ok with you) that way he won't feel he has to hide it from you. Also, you could tell him you'll "replace" it with pics of you. ;-) I think I'd make him show me the pics/videos just to be sure it's not something else (him cheating).