We encountered the same issue starting in the early morning of 10/2/2016. When we contacted support we were informed that the server that hosts our account was "under maintenance", but with no specific information as to what that maintenance was.
We were completely unable to run backups or access our account until yesterday afternoon (10/4/2016) when we noticed our scheduled backups began running successfully again. We checked the web portal at that time and were able to successfully log in again.
I am glad our backups are working again, but I would like more clarity from IDrive as to what happened. The support technician who worked on our ticket was not able to provide us with the exact reason for the maintenance.