OS X lookupd

I've just started having a problem on my Mac over the last few days: lookupd is pegging the CPU, turning on the fan and chewing up my battery life. lookupd is the OS X daemon responsible for, well, looking stuff up. It caches information about DNS, user accounts, NIS, and so on and so on; do a "man lookupd" on your OS X command line for more info.

For some reason, it's started, every so often, running absolutely nuts. This has started since I replaced my DSL modem, although I can't really conceive of how a new external piece of hardware would cause the daemon to use all the available CPU time. I suppose it's possible that lookupd is getting stuck somehow because the firewall won't let it through, but that sounds farfetched to me.

The temporary fix to the problem is to send SIGHUP to the process so that it will restart cleanly. This at least returns the lookupd process to status quo ante (yes, the second time I've used "status quo ante" this week), but it doesn't exactly help figure out what caused the problem in the first place. Time to start digging, I guess.

(By the way: "sudo kill -HUP ", where is the process ID of lookupd. You can get that with Activity Monitor or from "top".)