Runaway process (mdns?)

[vr8ce]

I have a runaway process. My CPU is running very hot (too hot to keep on my lap), and the fans are constantly running between 4K and 6K RPM.

iStatMenu shows it as mdns, using between 97% and 100% of the CPU (the top of the CPU monitor shows user at 22%, system at 35%).

iStatPro widget shows it as B23913F8…

But, interestingly, ActivityMonitor doesn't show any single process consuming over 3-5% CPU (and those are activitymonitor itself and sometimes Firefox), but the CPU usage on the bottom shows the same high usage that iStatMenu shows. So, AM knows something is using the CPU, but doesn't seem to show what it is.

I've tried rebooting, shutting down and restarting a few minutes later, and booting into Safe mode. In all three cases, the process is starting immediately; I can see the CPU usage with NO other program running at all.

This just started this afternoon, and I've installed no software or updates today (or yesterday). Google seems to indicate this might be mDNSresponder; there are instructions to turn it off in Leopard and prior, but it can't be turned off in Snow Leopard without turning off ALL DNS.

So, first, what it is?
Second, why doesn't ActivityMonitor show it, or show it chewing up CPU?
Third, why is it doing it?
Fourth, how can I kill it?

Thanks!

 

[-aggie-]

See these links:

http://discussions.apple.com/thread.jspa?messageID=5878602

http://forums.whirlpool.net.au/forum-replies-archive.cfm/1431602.html

Check your Console to see if anything has errors.

 

[vr8ce]

I do not have .Mac, nor is anything configured for it.

I do not see any constant error messages in console, either in "All Messages," "Console Messages," or "system.log".

 

[vr8ce]

I spent time with three different Apple Care specialists today (one 1st level, two 2nd level), and they eventually had me re-install Snow Leopard, which, as you might expect, cured the problem. Seems too close to a Microsoft approach to me (reinstall the OS!), but it is working.