Help please, our training room NEC NP-M300W suddenly shows 2 quarter circular waves looking pattern and black dots all over the projected area, only 100 hours in use since July 2011, filter is very clean, any connection (VGA, HDMI) will show that and even without any inputs, the stock in-built screen also shows the quarter circle wave pattern but very fainted, tried power off for a day, verified cables, source, believe it is the projector's own problem. Anyone experienced this before? The black dots basically rendered the project not usable any more.