Q: G5 kernel problem, Ram OK

My G5(Dual 2Ghz PPC, OS 10.5.8) does not appear to have outright kernel "panic" based on what I see looking at the console log entries.  ONce in the last day it appeared to "panic" but I found no evidence on the log.   The only key thing about it was the fans revved to full output and I had no keyboard or mouse controls.  I was forced to shutdown with the power button.   I keep getting THIS error when the fans rev for a bit(today)

Mar 11 14:41:19 G5  kernel[0]: {       41   810400} UniNEnet::restartReceiver

   . . .  but they just increase in speed a bit for a few seconds and go back to normal.

also, it almost continously pumps out THIS message:

Mar 11 14:40:31 G5-basement mDNSResponder[18]: ERROR: getOptRdata - unknown opt 65002

Mar 11 14:40:31 G5-basement mDNSResponder[18]: ERROR: getOptRdata - unknown opt 4

   . . .  every few seconds.

Would anyone know the function of MDNSResponder or the kernel entry above?  POssibly, might be enough to point in some direction.

I have already eliminated unneccessary startup items.

thanks!