windplayer

Hi. Recently i got myself used x-pro1. But it turned out that it overexposes most of the shots. At first i thought that its just some weird settings. Reset it. Updated firmware, and stuff, but it still overexposing pictures a lot. I use cheap chineese manual lens from 7 artisans btw. Just now i was able to isolate problem - it looks like shutter speeds up to 1\500 works fine, but all speeds faster - it seems like the camera fires same 1\500 again. From DSLR i know that fast speeds dies first, and dying shutter produce stripes on picture (or im wrong?) Pictures i take on 1\1000 and faster speeds have no stripes, they exposed uniformely from top to bottom, but just overexposed. All speeds up to 1\500 works just fine - i got normal pics. 1. Had anyone experienced this? 2. How long shutter can live like that? I know that it'll be good to have camera serviced, but dont have free buckazoids right now. I can live with 1\500 speed by stopping down the lens and using auto ISO instead auto shutter speed. Just want to know how long camera can run like this.