Check for other sources of light ...turn everything off and close the curtains and if the prob is still there you'll know it's not light interference.
Also ...try just gently pushing the wire at the back of the sensor bar in ...or get someone to gently move it in different positions while you point at the screen. If nothing changes you'll know it's not the wire.
Do you have another Wiimote ? If so synch it to your Wii and try that one. If it's still the same you know it's not your remote.
Do all that then report back
