How are you trying to connect the new unit? Are you using HDMI? Don't use Coaxial cable, it's not HD compatible.

You're not using any sort of cable signal booster, correct? That will cause problems.

Try to hook up your old tv to the new cable box. You won't be able to receive any HD channels but you'll see if the box works.

If the box works with the old TV, it's not the signal.

A week signal can cause problems, but not like you're having. It sounds more like a setting is not correct. Make sure your connected with a HDMI cable. You should have to set your cable receiver to output the proper signal to the monitor. For instance, my cable box required me to press 'info' and 'guide' on the box to bring up a setting menu.

Make sure that the Monitor (TV) is also set to the correct input. New monitors usually have multiple HDMI and other inputs.

Good luck.

Thanks for responding, klaa2. I had no luck going from the wall directly to the TV or from the wall to the TV via the cable box using the cable outlet my old TV was hooked to. I ran it to a cable outlet in another room, and now both the cable box and TV are working. The old TV worked fine in that outlet, but I couldn't get the cable box to even register the time and the TV wouldn't pick up any channels (analog or digital) when I went through the setup scan.

I'm using coaxial cable from the wall to the cable box and HD composite cable from the cable box to the TV. The cable box didn't come with an HDMI cable, but that would eliminate some cords. Should I get one? If I understand you correctly, after hooking up the HDMI cable, I'd need to set the cable box to output the HDMI signal and set the TV to receive the HDMI signal. Then, I'd need to go through the auto channel scan again, right?

I'm not using a cable signal booster, unless the cable company has one installed that I don't know about. Maybe there's a signal booster at the outlet that I'm having problems with and the outlet in the other room (that's working) doesn't have a signal booster.

I'm glad to know that the cable box and TV are both in working order, but it's scary having that cable running into another room. I'm kind of a klutz.

Thanks for your help!