Okay I'm probably going to need access to your account to check this myself - if you're comfortable with that. Try deleting the "Amanda added this" text from your signature. Does it work now?
1 > Try clearing all your cookies and temporary internet files from your browser. In Internet Explorer you click: Tools > Internet Options and then "Delete Cookies" and "Delete Files". Once done, restart your browser and try again.
2 > Tell me the browser and version you're using so we can check for known problems. (i.e. Internet Explorer 5.0; or 5.5; or 6.0; or Netscape 6; or 7)