As others have mentioned this error suggests that the key is tied to a corporate network that it must log into every XX number of days in order to remain active and once it has not logged in for an extended period of time the key will become deactivated (just like you say has happened) and in order to reactivate you will need to log into the companies server -- If you can not get onto the server you will need to purchase a new license since you are not an active part of the company and thus the install is not legal and must be changed to a legal stand alone license rather than the company license.