Kevin,
I've had this EXACT same problem in a 20 year old house. Everyone
said that a device to combine both 'phases' of my wiring would fix the problem, however the problem still persists when the dryer/oven is on.
That's the first thing you need to check. Turn your dryer on (which will combine both 110v sections of your wiring because it uses 220v) and see if that cures the problem. If so, you need to purchase a $50 device which combines them permanently.
If not, you're in the same boat I am - don't use an X10 switch on
that light :(
Thank you,
www.RRDeals.com