I got a job recently to repair the lock in an interior wood door. According to the customer the lock would not latch and it was very difficult to close. One thing I did noticed while I was messing with the door was that the top of the door above the lock was hitting the frame and in order to close the door I had to lift up on the lockset. Once I was doing that, I also noticed that the frame moved on the hinge side. I noticed that many of my fellow locksmiths ran into the same problem as well. For me It seemed like when these frames were installed the professionals who usually do the installation use dry wall screws to attach the frame to the 16 gauge metal stud. With the higher usage doors the screws often wallow out their holes and cause the doorframe to loosen.
The way I now deal with this type of issue is to remove the doorstep trim from the frame on the hinge side. Close the door, place an air wedge locksmith tool beneath the door directly below the lock and inflate it until I hear the latch click. Now I go on to install self-tapping screws with a 3/8" drive head through the frame and into the stud. It seems like this method works, and the trim will still fits nicely over the screw heads for a clean look.