When uncounted with an error 793 while accessing your Gmail, it only means that Gmail is having some problems in its response time for opening messages, switching labels, etc. This happens when there is a conflict between softwares in your computer, or a temporary problem on the Gmail server.
a) Switch to another browser. You can use Google Chrome, Firefox, Internet Explorer, Safari are examples of browsers.
b) You can clear the cache where your temporary visited sites or stored to load your browser faster.