Can anyone help me with my w2207 LED Monitor? The menu button won't work and it constantly says no input signal. When it comes on it is in VGA mode and I can't change it to DVI. When I bring it to the shop it works and when it first gets home for a couple days it works, if I shut it off for a couple days it does it again. I have tried new cables, unplugging everything, checked for bent prongs ?