Most obvious possible source of the problem is the USB connector. Do a visual check and use some compressed air to blow out any dust/etc that may be stuck in there. If for some reason there's an intermittent short between pins 4 and 5 on the USB jack this will happen. The only other obvious solution is to manually set device to device mode instead of OTG mode, but again I would check the physical connector first. This problem will have arisen after upgrading to 2008 since that is the first OS release that supported automatic OTG host-mode.

Thanks,
-Rob