Mac, TCP question

Our resident Photoshop guru recently upgraded his Mac OS to v9.
Now any large file (roughly a meg or more) that he attempts
to FTP to our web server hangs after a few Ks worth has transferred.
Trying to attach the file to an Email also fails - his Email
client connects to the SMTP server and then it just sits there.

Any ideas?  I know nada about Macs but it sorta feels like
some kinda TCP window size problem to me...?

(Why are we sending a meg-sized image to the web server?
It's a high-rez .tif file of a screen shot of a web page
for the customer to print.)

 -John Koch                               -  -  -  __o
 Knowledge Systems, Inc.              -  -  - -  _ \<,_
 <John.ksi(at)webplus.net>                   - -   (_)/ (_)
 (A NET-FRIENDLY SIG. http://www.ncsa.uiuc.edu/Edu/ICG/pt1.ch2.Etiquette.html )

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