Mirc is at version 6.16, so i have a feeling version 3.72 might be something else (i think thats invision version number somehow, seems familiar), anyway the problem is in the NETGEAR router, its using a port remapping system, you say your sending on port 5001 (example dcc port#) which you do send on at the PC and it remaps that to port 50106 (example#) as it passes out the router, and it also alters the message to the reciever to say port 50106 rather than port 5001, this is all fine untell the reciever asks for a resume, since he asks by stating "can i get a resume on port 50106 at somesuch locaton in the file" and your mirc just goes ?!?!?!?!?port 50106?!?!?!?!?!.
I have read that you may be able to correct this problem using a IRC server port other than 6667 or 6669 , try connecting to the IRC server on 7000 if it lets you, as it might be that the check to adjust the port only functions on messages passing through the 6667 and 6669 ports to the irc server. (this solution is untested by me, but was said to work by others)