When a license for PGP Desktop expires, it may force the automatic decryption of drives encrypted with Whole Disk Encryption.
This can occur under the following scenarios:
Because the license is stored on a per-user basis, an infrequently-used user account can end up with an expired license. Once used, it can trigger this issue.
Upgrading to the latest version of PGP Desktop can provide a solution to this issue since it has a different license behavior. If you have upgraded from a previous version of Symantec PGP Universal Server and have input your client license, it will be used instead of the default license.
This primarily occurs with PGP Desktop 9.x in a managed environment.