I agree with Tom. CFCL's are good possibilities. There are ways to dix the problem. Basically a better repeater.

See if you can correlate to times the lights are on or even the AC blower. Look at alternate sources of light.

You might want to try a cardboard tube over the sensor. You'll have to have better aim, =, but it will cut off the majority of ambient light.

For now, make sure the remote isn't causing it too. Put it in a shoebox when your not using it.

Ceiling fans are another possibility.

I had an issue with an X-10 system not working when the AC blower was running on a carrier 58mVB furnace, A $70 filter installed at the furnace worked wonders. There is no RFI filter which is stupid.

To further help other issues, a bidirectional transorb was placed across R and C.