Try here and here.

Since the spare remote doesn't work either, it's most likely not a problem with the remote, but rather the player's IR receiver. Although do check both remotes with an IR-sensitive camera viewfinder to make absolutely sure they're sending signals. If those work, then do the diagnostic step at the second link (looking at proc/empeg_ir for missed interrupts) and see if that's what's happening to you.

Also make certain that you're using player software version 2.0 final. Certain alpha and beta versions had problems that would make it seem like it wasn't responding to the remote.

Also activate your disk drive indicator icon... If the lack of remote response happens only when the disk drive is being read, then you might be having disk trouble.