Is there a substitute for the wii sensor bar?

The name "Sensor Bar" is a misnomer. It doesn't sense anything.

It does provide the IR camera on the front of the Wii Remote a couple of IR beacons for it to triangulate with. The Wii remote sends back the image it reads off the IR camera, and the Wii uses that to figure out where to put the pointer on screen.

Any IR light source will work. Do you have a Christmas Tree set up? It may be picking up the IR off your tree's lights. Sunlight can also interfere with the IR camera. Any windows nearby that get direct sunlight?

You can find wireless Wireless sensor bars anywhere Wii accessories are sold - they're about $20. You can even make your own with about $5 worth of parts from Radio Shack (a couple IR LEDs, a battery clip, and a resistor. Some people house them in a body made from Lego bricks).

lit candles (usually long-stems work better)

incandescent lightbulbs

cats

basically any heat source

If you want to try to figure out what is causing it easier, go into your Wii settings, to Sensor Bar, then Sensor Bar Sensitivity. Whatever IR signals the Wii Remote camera is picking up will show up as dots on screen.

Dude, believe it or not, you can use 2 lit candles instead! just place them about a foot apart on your tv. Try it!