Anytime a rogue with this talent successfully hits an opponent with a sneak attack, she may forgo her sneak attack damage to try to hamstring her opponent. If the attack succeeds, the rogue deals weapon damage as normal, but instead of the rogue dealing sneak attack damage, the target is knocked prone and is unable to take move actions during its next turn. A successful Fortitude save (DC = 10 + 1/2 the rogue's level + the rogue's Dexterity modifier) negates this effect.
I was talking to my friend about this and we had different I ideas of how it worked. He thought you could take a full round action but nothing that would be a move action like standing up of drawing a weapon. I thought it meant that your move action for that round was just gone. Is there any official word on this?
I agree with your friend. Your opponent can take any action that isn't a move action, including full round actions. They just can't go anywhere. As it's written, move equivalent actions should be allowed but I'm not sure I'd allow them to stand up (a move equivalent action)