Microsoft Security essentials update wont allow me to sync with my Drop box account on my machine

Hi There,

would any one be able to advise me on how to change the firewall setting in Microsoft Security Essentials. Since Microsoft Security essentials updated 2 days ago I can't sync with Drop Box. I know I need to change the firewall settings but can't find these when I open up Microsoft Security Essential on my machine. Prior to this update I had no difficulties syncing with Dropbox.