As far as testing the 15 by attempting to control a module plugged into the same outlet I have to hand it to X10. In the past you could run 110 through the 11a. Not so easy now. Once I plug the 15 into the house outlet, there is no room for any modules.
If you have an extension cord with multiple sockets at the end (NOT a surge protector), you could plug the CM15A into that, and have at least one free outlet to test with.
I can tell you that when the laptop is connected to the 15, I cannot turn anything on or off from the computer screen.
Since it is a laptop, does it have a good enough battery to run without being plugged into the wall for a few minutes?
Try unplugging the power adapter from the wall, and see if that makes any difference. Some laptop power supplies generate a lot of powerline noise, which can drown out the CM15A's signals.