I've never tried the 18" placement, but can give that a try as a test.
I am sure that you have tried the obvious... rebooting the TiVo, rebooting the DirectTV DVR, checking the TiVo's IR setup to control the DirectTV model you own...
Since it is likely that the IR link is the source of the problem, you might try swapping out the TiVo's IR transmitter with another one. Know anyone else with a TiVo? I received an IR transmittor with each of my TiVo's, but don't use either one. Maybe someone near you has a spare or can swap with you to test it.
Next, see if changing channels with your DirectTV remote works well... this will test the IR receiver in the DirectTV box.
If still flaky, the only circuit left is the IR driver chip on the TiVo motherboard. If you have a lifetime TiVo contract, get it fixed (I can give you the name of the company that can do it). If no contract, consider getting a new TiVo! They run specials on the new HD Dual Tuner TiVo's ocasionally.
Good Luck! ************************************************************************* ** List info, subscription management, list rules, archives, privacy ** ** policy, calmness, a member map, and more at http://www.cguys.org/ ** *************************************************************************
