That sounds to me like a borked iMon driver, or perhaps a damaged remote. The remote being damaged, however, would probably do it even after a reboot. But who knows...
However...
Another thing to try, is to reposition the iMon
receiver. I have absolutely seen, and heard about (
to hilarious effect), IR sensors being tripped by all sorts of stray light. In particular, fluorescent lights (like the "twisty lightbulbs" everywhere now) are common sources of interference with IR sensors. I've seen it happen with TVs that mysteriously turn themselves on and off, change channels randomly, and stuff like that.
I also was unable to take my old Macbook (the weird aluminum, non-pro one Apple made for a year or two) into certain rooms at work because the lighting would trip the IR sensor on the laptop (even when closed and asleep) and trigger the Volume Up command. So, you'd walk into the room, and if the laptop was out, it would continuously make the Apple "volume up" clicky noise (at full volume, of course). And, you couldn't mute it, because the Volume Up command would, of course, unmute the system.
Was pretty funny, actually.
In any case, you might be actually getting "stray" commands on the iMon generated by things other than the remote. Try moving the sensor, or lighting around, particularly while it is happening, and see if you can make it stop. Maybe kill the lights and throw something over the sensor? Then, if it keeps happening, you know it is "driver related" (or broken iMon hardware). If it does stop, the problem is external.