ICS Error Message

I have a desktop networked directly to my laptop via a crossover cable and the network appears to be working ok. When I try to enable ICS on my desktop (host) machine I get the following error message "An error occurred while Internet Connection Sharing was being enabled (null)." I have a Surfboard SB4100 cable modem and like I said the network appears to be fine, I can ping all the IP addresses listed, the problem seems to be confined to my host machine being setup and enabled or maybe it is the modem. Anyone have any ideas?

 

RNAAPP generated error (761? - the (null) at the end is a little strange). The fix will depend on your operating system.