Page 1 of weird"flash" accross philips widescreen tv????

hi guys,can ayone help?i have had my 32 wide philips for about 2 years now,every now and then a "flash" goes accross the screen,it could be when i watch sky,dvd or normal tv.it does not happen all the time but it always does happen from time to time.could it be the tuner,is it some connection that is wrong with what i have plugged into the tv {my sky box,dvd??} it is very annoying and i dont know what the hell it is? can any one suggest what it is?the tv plays fine and have no bother with it what so ever except this.it is starting to make me potty!please help.