If the disk is already instrumented, i.e. due to a previously failed encryption attempt, the encryption will fail with an error.
If the internal user policy required automatic disk encryption the initial enrollment will fail.
An Error Occurred - PGPError #-12291
PGP Whole Disk Encryption will fail if the disk is already instrumented.
To resolve this issue uninstrument the disk using one of the following:
1. Uninstrument via pgpwde commandline using the command:
pgpwde --uninstrument --disk <number>
Where --disk specifies the disk number to be uninstrumented
2. Uninstrument by starting PGP Whole Disk Encryption, then select Pause and choose to decrypt the disk.
PGP Desktop 10.2 (as well as all PGP Desktop 10.x versions)
Mac OS X 10.6.8 (this may likely occur on other Mac OS X versions as well)