Power lines can conduct interfering signals into and out of equipment. If the laptop has a battery capable of holding enough charge, simply test by unplugging the laptop. You may be able to find a snap on ferrite EMI choke at Radio Shack if you prove the power brick or laptop is generating interference. See:
http://www.radioshack.com/product/in...ductId=3012599 and
http://www.radioshack.com/product/in...lickid=prod_cs If you try ferrite chokes, place one over the TV power cord close to the strain relief as it enters the TV chassis.
Coax to power line or CAT-V crosstalk is far down on my list of suspects provided the coax ends are terminated correctly. An open or high resistance shield connection at the F-connector would leave the coax open to all the local interference in the home near the bad connector. Even a connector that has not been tightened adequately will be a possible 'open shield' problem. (But don't over torque F-connectors.) A DC ohm meter can be used to trouble shoot opens and high resistance in coax. Simply wiggling a connector may produce a visible result on screen, but with DTV forward error correction, you're not guarantied you'll catch a bad connection every time. The bottom line is, the only place desirable and interfering signals should be able to enter the coax is at the antenna. If the shield is properly connected at every point, standard coax is extremely effective at accomplishing that goal.
CAT-V can be installed incorrectly. One common error is 'split pairs'.
http://en.wikipedia.org/wiki/Split_pair Split pairs cause the wires to be far more susceptible to receiving and radiating interference. There are two common color codes in use. I recommend that you use only one method throughout the entire installation.
http://en.wikipedia.org/wiki/TIA/EIA-568 Most commercial CAT-V is installed using the T568B color code. If your installation is using T568A, continue with that standard, the Ethernet frames don't care about the color of the wire insulation.