All the X10 modules display this "current leak"--it's actually a feature.
You see, by allowing a small current through a device, you can detect when the non-X10 switch on the device is switched off. That way, if you don't have a remote control handy, you can still turn a light on by just cycling the device switch off and on.
Other vendors sell modules with a programmable current sense mode which can be disabled. X10's modules must be disassembled and a wire on the circuit board snipped to make the change. For details, look at:
http://www.idobartana.com/hakb/index.htmThe X10 lamp module was designed for 40-300 watts of incandescent light, which won't power up with the trickle of current. Those little candle lights are just too darned efficient.