I encountered the same issue yesterday with 2.7.11 alpha. I tried to turn on a lamplinc and due to Insteon communication issue, ISY is unable to turn on the lamplinc and threw an error. Since then I get 'System Busy'. I closed the console and tried opening it again in two different PCs (totally tried from three systems, one of them is Mac). Finally I gave up and unplugged ISY and plugged it back.
Can any expert comment on this? This is a serious issue for me, as sometimes I will be controlling ISY remotely when I am not home and it would not be possible to power cycle the device.