FTP problem between Solaris 2.8 and NT

I am experiencing sporatic problems between my Solaris 2.8 server and a NT server. I am doing an “mget” from the Solaris 2.8 server. Sometimes it the FTP will hang, NT server has the session closed yet process still running on Unix server. Will hang on the “150 Opening ASCII mode data connection for xxxxxxx”. Also other times I will see “No control connection for command: Transport endpoint is not connected” in the mail message from the CRON command. CRON executes the FTP script every 30 minutes. Suggestions?