Norton toolbar causes ebay problem when using Firefox 26

I have Firefox 26 and Norton 360.  When I try to ask a seller a question on ebay, I have to enter a code displayed on the screen. The code is ALWAYS rejected when I use Firefox. (It happened with the previous version as well, but not with IE.) I turned off all of the Firefox add-ins one by one until I found that Norton Toolbar is causing the problem.  Any solution? Thank you.