Adding that one code to the cable box and then sending the file to the remote somehow makes no functions work -- i.e. the TV functions don't work, the Blu-Ray player functions don't work, the receiver functions don't work, etc.

But yet reverting and reinstalling the old file fixes everything back to normal. That's why I suspect it has something to do with how I am sending the revised file to the remote that is causing the problem, since it's unlikely that adding one cable box IR function would screw up all programmed functions across the board, no?