I have an Apple Remote that I haven't used for a while and can't get it to pair nor function with my iMac, I am wondering whether the infra-red sensor is not working, its either that or the battery. I've tried a new battery but it didn't resolve things. Could be that last time I took the iMac apart a connector on the infra-red sensor came dislodged without me realising it. I looked in About This Mac > More Info > System Report (Same as Applications > Utilities > System Information) and can't find any data about the infra-red. I am sure it should be listed under the USB section of Hardware. If someone with the same machine could check for me and post a screenshot of the detail page I'd much appreciate it.