I understand it like this, you refer to this one:
http://www.symantec.com/docs/TECH173502
It says:
"....... Problem Description
The problem occurs as soon as FileVault 2 is used to encrypt a drive on a machine that has Symantec PGP Desktop installed. As soon as the machine is rebooted after initiating encryption, the machine is left in an unbootable state ......"
And this is what happens for me, on several computers.
1. PgP is installed. NO DISK ATTACHED, NO WDE ENCRYPTION CONFIGURED
2. File Vault 2 switced on = CRASH.
3. Solution:
Delete these two files, before switching Filevault on (this will leave PgP to function OK in terms of clipboard encryption, key management, file encryption):
/System/Library/Extensions/PGPwde.kext
/Library/PriviledgedHelperTools/com.pgp.framework.PGPwde
BR Asger