Is anyone familar with door latch problems?

My door started acting up two weeks ago doing this anoying thing where it doesn't latch and just bounces back open if i shut it when the door is unlocked (happens 2/3 the time) but if I lock the door it latches shut every time. Now last night a new problem showed it's face but fixed itself before I went to sleep - I couldn't open the door from the inside!!! I had to roll down my window and open it from the outside and after the third time of having to do that it stopped. I also noticed it felt like the locking system was binding and not easily switching from lock to unlocked. It's the driver's door and not the passanger so I wondering if it's just the latch worn out. The driver door panel is rigged and is a extreme pain to get back on right and after dropping a ton of $$$ into the suspension of this car I'm not ready to just start changing parts that might not be bad...has anyone had this problem before? what in the end turned out to be the culprit? thanx