Is this a cloud version or locally hosted version of AC? AC often freezes up in both situations. When I hosted AC locally and accessed remotely I would hit ctr-ALT-delete (in the host computer, or just right click on the task bar), open task manager, close ac service or app, and restart ac and it would start up easily. If you are on AC cloud service you are at the mercy of their tech support.

Gerardo Carcamo
Surgeon
San Antonio, TX