Can Norton make FTP keep getting interrupted by error messages during uploads?

I am running an inventory management and listing tool for internet auctions. It has worked fine for many years, but a problem has emerged recently. When I upload the auction listings, the programme begins by uploading all the associated images. This should be quick, even with quite a large number of images. What has started happening is that after , say, 10 successful uploads, it comes to a halt, pauses for about 15 seconds, gives an error message about not being able to connect to the FTP server. It then uploads another 2 or 3 successfully, and then the same pause and error message appears. And so it goes on.... With several hundred images to load, it means the process is taking perhaps 20 minutes or more, instead of less than a minute. The problem only happens when I use the programme. If I use a separate FTP to test uploads, they go up immediately, so the problem seems to be related to this particular programme. The people who supply the programme ran tests their end using my database, and it worked fine, so the problems seems to have been isolated to how my particular computer interacts with this programme. I am running Norton 360, and wondered whether any of the settings might be treating the FTP withing this programme as suspicious, and keeps interrupting the process. The programme is 'allowed' in the Norton list of programmes. any help or suggestions very much appreciated! Thanks