After trying to get PC monitor to work with my SQL 2012 dev edition, it was a simple fix;
Set the PC Monitor service to run as a user that has database permissions (I chose local server administrator) and choose "Use Windows Authentication".
Otherwise just set a SQL user up with 'public' and 'sysadmin' server roles and put them in the authentication settings.
Hope this helps someone!
Thanks,
Ollie
EDIT: Also a small app dev thing; tabbing order is a bit strange on the SQL Server settings page!