[henryd_il]

I'm having trouble debugging a file transfer problem.
My setup is as follows:

Computer A is WinXP running Windows Messenger 4.7
Computer B is WinXP running Windows Messenger 4.7 + Kerio Firewall
Computer C is Win98 running MSN Messenger 6.2 + Kerio Firewall

File transfers between A & B are fine
File transfer between A & C are fine
File transfers between B & C always fail with the message 'file transfer timeout' that occurs immediately after B accepts a file from C.

What I fail to understand is that if mixed OS/Messenger such as between A & C works, why does the same mix between B & C fail.

Suspecting a firewall config issue I deleted all Messenger,Internet Explorer and Outlook Express entries from the Kerio instalation on machine C.
After firing up Messenger on C, Kerio then alerted me with all connection requests by Messenger which I permitted.
After this excersize transfer between A & C worked but not between B & C.