I have a Panasonic PT-AE700U with 300 hours on the bulb. It works perfectly fine watching a blue-ray but flashes white noise on the screen every 3 seconds for a half second when watching HD cable tv. This just started happening. The cables are tight. All cables go thru a HDMI switch then one long (25') HDMI to the projector. The projector is set to "high" output. No sign of overheating... Any ideas?