I have a streamzap remote that has worked ever since I built my box, but occasionally the frontend will no longer respond to the remote. When this happens I:
ssh into mythbox
exit mythfrontend through keyboard
restart lirc
start mythfrontend

And the remote magically works again. Is there a log anywhere to troubleshoot this? I did notice that when I had a paper shredder plugged into the same outlet, I would see this happen almost every time I used it. I moved the shredder it to a different room. Now it just happens once in a while, but if somebody else is watching tv and I'm not there to fix it, then they can only reboot the machine.

I'm seeing a similar problem with a homebrew serial receiver. Have you tried restarting the frontend without restarting lirc? I'm not seeing any errors related to lirc in /var/log or its subdirectories.