i have noticed this problem on a dozen different comps using various os from win2k to win2k3 sp1.
When using a proxy for dcc i sometimes(not always) get the first 1024 (sometimes more i think) bytes of the dcc-ed file lost and replaced by 0
s
it seems to be randomly happening and that with may different proxy softs
it doesnt seem irc network dependant since ive seen it happend on many different networks
also its not linked to a nat/firewall prob since it happened on both direct connections to the net and firewalled one(i tested on half a dozen different connections)

anyhow thats it

note: most of the time i was running a ssh -D proxy but i doubt its in cause for the problem since i used various ssh/sshd clients/server and the problem appears everytime, not to forget it works perfectly for all the other applications