Slingplayer Help - Screen dims/turns off

Occasionally (but not consistently), when I turn on my slingplayer app on my iPhone 3g (not ios4 software), the app works fine for 30-45 seconds, but then the screen dims, as if it were any other app where the phone is about to go in autolock mode after inactivity, and then everntually turns off, all while the audio works fine. Its acts like its just an iPod app. I've had this problem on 3G and on Wifi, but like I said, it is not consistent and only started happening within the last few weeks. Is there a setting I changed on the phone/app by accident? I can't figure anything out and the Slingbox support people are totally useless.