Just recently, I've started to notice some light horizontal bars move up my screen when watching HDTV. They may not be noticeable to someone not looking for them but I do... wouldn't we all in this forum?

Anyway... I've been using the same component video cable with my InFocus 4805 for a while now and it never used to happen.

My PS3 looks great, no bars.

I have other electronics components around the cable box like the PS3, wireless router, modem, vonage. The cable box in on top of a shelf system and all this other stuff is beneath it. Everything is well ventilated.

Thanks in advance for your thoughts.

Sound like a ground loop problem. Have any electrical connections been changed or has the cable company been out and screwed something up?

By electrical connections to you mean the power cord for the projector?

Would a split in the cable connection cause this? I've recently had to split the cable coming in to accomodate my modem. The signal strength is very good, so I thought.

If this is the problem, would an amplifier do the trick?

It does sound like a ground loop to me also and is pretty common complaint with cable boxes. Comes up here every month or so. Some easy tests to try to see if it is this is plug the projector into one of those cheater plugs that are used to go from a 3 prong to a 2 prong. Another is try a extension cord into another outlet on a different circuit and see what happens.

Do a search here on ground loops and you will find lots to read.

There are isolators and surge suppressors that can help if it is a ground loop. Do a little reading below and see if it sounds like what you have.

Google brought up these reads.
http://www.cinemasource.com/articles/gnd_loop.pdf

http://ecmweb.com/mag/electric_finding_fixing_ground/

http://en.wikipedia.org/wiki/Ground_loop_(electricity)

http://www.answers.com/topic/ground-loop

Thank you for that detailed response. I will try your suggestions and do more research within the forum. I would have done that sooner but didn't understand the concept of a ground loop... until you educated me.

Again, thank you.