FTP problem between Solaris 2.8 and NT

Are you going through a firewall? I have seen some cases with Check Point firewall (I'm sure ohters have the problem too) where this exact thing occurs. What happens is when you FTP from a box to an FTP server you open port 21 from the client to the server to establish the connection. Then when you do an ls/dir or request files to be transferred (any data connection) a connection is made from port 20 on the server back to a random port on the client. The problem is if the random port happens to be defined as a service in the firewall. Check Point (and I'm sure other firewalls with the problem) do have work arounds, but it isn't advised if it is an internet facing firewall. Since the random port is over 1024 most people don't see thisproblem because most people don't define services on ports greater than 1024, they just let them connect randomly and identify specific sources and destinations. The other work around is to try a passive ftp tool such as the freeware wuftp. This will make the data connection in the opposite direction and will not use port 20. So all ports used will be greater than 1024 and you don't have the violation of a protected port (<1024) initiating a connection to an unprotected port (>1024). Here is a good site that explains active v. passive FTP in more detail.
http://www.slacksite.com/other/ftp.html

Good luck.