Hmmm.... tried setting one or other box to a different IP, but no change to the symptoms. When you say 'disable the modem's router', I assumed that's what the bridge mode achieved. Do you think there may be more fiddling required? I think I can disable the modem's DHCP server while leaving its DHCP client active - would that help even if it's in bridge mode?
Trouble is, I'm on the second Creative modem and I'm rapidly coming to the conclusion that the whole caboodle is rubbish! Maybe I should bin the lot and start again with an integrated modem/wifi router?
Computers, eh???