I am transfering a file using FTP to my web server and at the last step of "put" the command line freezes. Any ideas to the cause? or any ideas how to track down the problem?

I been in contact with my web host and they have said they can transfer files just fine. The other interesting comment is sometimes this actually works. But most times it does not. I can open the ftp, logon with user id & password just fine. I can change directories on the server but after excuting the put the command line just hangs.