I finally was able to go back to the customer's home tonight and try a few solutions:
1) I installed an emitter to the Comcast STB and removed the IR blaster.
2) With the help of URC tech support, I removed numerous traces of code 195 that were still lurking on the CCP program. All were replaced with code 202. For example, the "enter" key was not overwritten with code 202. It was still code 195.
3) I moved the MRF350 and it's antenna at least 2 feet from the cable box.
----You guessed it...problem still persists.
I have tested my own MX990 at my own home with one of my MRF350 sytems, using the client's CCP program. Problem does not duplicate after testing over 40 favorite channel macros.
I am down to suspecting the customer's cable box (and/or it's firmware). My instincts tell me that's wrong. It is not a DVR, but neither is the unit in my own home. My own STB has no brand, but model is RNG150N. The customer's STB is a Pace PX022ANM (AKA: XG2v2-P). It has the same symptom on code 195 or 202. The only difference between the client's system and mine is the STB. Getting desperate! HELP!