PGP Desktop disks not mounting after OS X 10.7.4 update

Some users of Symantec's PGP Desktop encryption software are finding that after installing OS X 10.7.4, the program does not appear to respond properly and encrypted disks can no longer be accessed. When attempting to mount the drives, nothing happens, and the program states in its logs that the disks are already mounted. 

This problem seems to be specific for users who installed the OS X update when using versions of PGP Desktop prior to the recently released version 10.2.1. If users upgraded to 10.2.1 before installing OS X 10.7.4, then the problem does not appear to surface; however, once the problem has surfaced then upgrading to 10.2.1 after the fact does not seem to correct it.

To avoid this problem, be sure you install the latest version of PGP Desktop before upgrading to OS X 10.7.4, but if you have not done so then this bug will prevent access to files on your PGP encrypted volumes. However, PGP Desktop user James M. Madden figured out a workaround that will at least allow users to regain access to their files from the encrypted disk.