For anyone who is having issues with Island Rum closing and nothing opening - close Island Rum, rename the 'coh' folder inside /Applications to something else (e.g. coh.old) and then try reopening Island Rum. It should recreate the link.
For anyone who is having a DBServer error when selecting the server, open a terminal (/Applications/Utilities/Terminal), and type in sudo ifconfig lo0 down, then hit enter, type your Mac OS login password (keystrokes will not be printed on the screen as you type them, this is normal) and hit enter again - then try logging in. This is a temporary fix to the DBServer error but I've tested it on two machines now and it seems to work.