ntop strange message

[UnKnown <rak@burst.fcien.edu.uy>]

Hi everyone,
I resently install the ntop package in one box to tray it, since the first
day I started to recive this info with the log check report. I think its
related with the name servers or something but cant get why, how to fix it
or where is the error,
minerva2 is the server runing the ntop and pc_05 is the local network
machine tis sime to be windows names..... 
Feb 21 18:31:48 minerva2 ntop[21759]: WARNING: Malformed ICMP pkt
pc_05->all-routeers.mcast.net detected (packet too short)


this message repeats several times with diferent local machine names gut to
the same destination.

I would apreciate any help u could give.

Cheers,
	rak