I kept getting "unable to retrieve patch data (311)", and several guildies have had the same problem you did.Apparently some people have been having problems with their hosts.
Remember to kill repair droids in the back so they don’t heal rest of the adds.
Recently I have been playing Star Wars: The Old Republic. I am a fan of most everything Star Wars, so, I had to try it out.
Sadly, after playing for a few weeks, I was greeted with this: Skip to the fix… This time, the same error, “Only a single instance of this application can run”.
But, I uninstalled it to try to fix something else.
Before I uninstalled it, I made a backup of most of the files in another directory. no additional release patch between first and second installs), I decided to re-install it with the web installer again.