Just discovered last night that I can't get screenshots either. Hitting PrintScreen doesn't crash my game, even though I did it about a dozen times sitting right smack in busy Wili harbor. (Last time I tried this with all my mods enabled, it eventually CTDed.) However - when I exited the game, I couldn't find what should have been the newly created .tga files anywhere. Even doublechecked to see what folder I had them directed to, and... nothing. It's like the pictures failed "develop."
I opened PSP and tried to paste the last copied image in there as a new image, and got an image the size of my game area that was just black like what I get in ME now.
So I don't know if it's a memory issue or the same thing that's causing the problem in ME... I may just create another game installation to run at the stock resolution without any tinkering and see what happens.