Mitel Engineering recently worked on an issue that turned out to be related to a recent Microsoft update.
ENG-560380 - "ShoreTel Contact Center Service" fails to start when starting from "Services" window.
Some customers were reporting other odd issues shortly after these updates were applied. In most cases, removing the update resolved many of the reported issues.
The final resolution was a newer update from Microsoft.
See the links below:
These are the updates for Win-2008 Servers:
Win-2012 Server Updates: