Try the following to recover access to your disk.
Run the following commands from "Program Files\PGP Corporation\PGP Desktop" to try and authenticate to the hard disk then decrypt.
To check disks of a system type: "pgpwde --enum"
To check the status of a disk, type: "pgpwde --status --disk <disknumber>"
To list users on a disk type: : "pgpwde --list-users --disk <disknumber>"
To authenticate a disk, type: "pgpwde --auth --disk <disknumber> --passphrase <passwordhere>"
To decrypt a disk, type: "pgpwde --decrypt --disk <disknumber> --passphrase <passwordhere>"
To recover if entering the passphrase fails, type: "pgpwde --recover --disk <disknumber> --passphrase <passwordhere>"
If you are able to recover access to the disk using this method backup the data, decrypt and run a full file system check and defragmentation utility before re-encrypting.
For additional commands for WDE see the following KB article.
http://www.symantec.com/docs/TECH149100