XPS One 2710, No Video Signal and BIST (Dell OSD Problem?)

Over the last month or so my Dell XPS 2710 often goes straight into the LCD BIST (Built in Self Test) on boot and when I awake it from sleep in the morning for the first time. It then cycles through a series colours—red, green and blue and then a combination of black and white—as a test for the display. Now, my LED touch buttons for screen control aren't working—they have never worked properly from the beginning—so I cannot stop the BIST by switching input to the computer. But after about an hour, sometimes less, the colour cycling ends, and I get the option to use the LED touch buttons to switch from no video signal to the computer. Though to my surprise at this point, the buttons work and the normal screen returns. Everything is fine except the LED buttons revert to their former unresponsiveness. Each day I am still at the mercy then of the PC going into the BIST; and that what's has happened to my Dell on each of the last five days. (Today it took 3 hours to get the screen back.). I think it's connected to the Dell OSD software, at least in part, but I have no idea how or what I can do to fix the problem. I have tried reinstalling the Dell OSD, and I have run the full Dell ePSA diagnostics and there are no reported issues. If anyone has any ideas, please say. Thanks very much!