cfftp Error Code 82

I am trying to use cfftp to upload files from our coldFusion server to our file server but about 50% of time, I get this error when system tries to make a connection. I am trying to upload 2 files at a time when I submit a form and I am trying to connect through cfftp, upload file then close the connection and then repeat the procedure for the second file. The first file is small (less than 400 K) and it almost always go through but when the system tries to connect for the second file, it throws cfftp error code 82 and its description says 'invalid server's version string'. I am using ColdFusion 8. I am using a timeout value that is much more than sufficient for files that i am trying to upload (in case, timeout I am using is 3600 seconds) and I am using secure connection. The problems remains there if I try to use even the non secure (regular ftp). Please help what this error is and what should I do to rectify the problem.
Thanks for your time and concern in this regard.