Groovit
Interesting you mention the endless channel scroll thing. I must have been using those codes because i had that happen and it was driving me nuts triing to figure it out. I used differnt codes and it was all fine.
As for the other problems being discussed. i have also had the best results with RS232 however when i need to use IR on those and any devices for that matter I always modify the equipment to have the emitters buried inside. i use blink emitters so I can see that they are getting IR. This has for the most part always given me good results. I few exceptions include using IR receivers with no processor in this case DTV won't work well unless you use a specific ir receiver.
I have found only one so far that works the xantech plasma proof model however there might be more now. There are also may tricks you can use to learn tough codes. Try learning the codes by holding your hand over the front of the remote you are learning hold the button down that you are learning and pull your hand away and back again as quickly as you can sometime that seems to work. The dtv boxes are way sensitive and can be a pain. Hope this helps.