In my experiences....if you leave the top in any partial position (partially open or partially closed), the top will retreat to the fully "top down" position after about 15 minutes....at least on my 2005 Roadster Limited. I have seen this happen several times and have personally timed the event, and have never experienced the issue you are having. On my 2006 XLR....there is a fail safe built into the top...it will close (top down position) automatically if left in a partial open/close position. Maybe your issue is switch/sensor related.