ATV3 Remote & my iMac

When using the ATV3 remote to navigate settings on my TV it also controls the iTunes volume and tune selection on my iMac.
My son's playing an online game on the iMac and I'm busy selecting songs and messing with the volume for him. He's about ready to throw something at me.

As well as my macbook, I sometimes stream content from the iMac as well and don't really want to un-pair it.

Is there a simple solution to this?

You pair the remote to a single device or you leave it open to work on all.

But you can pair/unpaired at will so it's easy enought to chsnge

The other option you have if you don't want to use a remote at all with the iMac is to just disable the iMac from accepting commands from the IR remote.

If you're using Lion, Go to:

System Preferences -> Security & Privacy

Make sure the page is unlocked
Click the advanced button
Select Disable Remote control Receiver

You can always re-enable it when he's done playing games.