Zeb is mostly correct in his assertion that people with long arms will have shoulder problems. There are a few things you can do that have worked for me. First of all, my wingspan is 76 inches and I am 72 inches tall so I have gorilla arms.
Anyway, you can just stop benching and start doing dumbell-presses, which is what I did a few years ago when my shoulder began to pop. I have been benching again lately without pain or popping because I changed my posture.
What I do now is PUFF my chest up and out as far as possible while keeping the entire length of the spine straight and flat on the bench. I also tuck my chin into my neck in order to keep that part of the spine straight. The belly-button should be sucked into the spine as close as possible, this will help you open up your chest without arching your spine. Also the scapulae should be pulled back as much as functionally possible.
During the actual bench movement I have found it to be less stressful on the shoulders if I keep the elbows pointed toward the feet as much as functionally possible.
I do similiar posture and keep my elbows pointed as straight backward as possible for bar-dips.
Someone else mentioned rotator cuff excercises, these are good. Search this site and find examples of those.