Probably the right forum, but definitely a very challenging question!!
It sounded like, though I'm not 100% sure, you have at least two remotes, plus the iTach that you are having this issue with; and the issue manifests itself on several pieces of equipment. The chances of this being due to simultaneous failures is......remote!
My initial reaction is that something has been introduced into the environment that is interfering with the IR signal - this could be a new lighting fixture (or bulb type), or some other device, probably independent of your AV equipment, that is emitting something that is confusing the IR sensors in the target devices.
There was another thread in the forum a few weeks ago where sunlight was being bounced off a swimming pool outside of the viewing room and was interfering with a projector. Silly question, but does the problem happen during both day and night? [If only during the day, you might have a strange reflection occurring, if only at night, I'd suspect some form of emission from another electrical device.]
Bottom-line is that I have no idea what this could be, but maybe someone else will chime in - the more the merrier!!