When encrypting a disk, the process hangs at 99 % and you are unable to Resume or Stop and restart encryption.
Open a command prompt window, change to the C:\Program Files\PGP Corporation\PGP Desktop directory and run the command below:
pgpwde --decrypt --disk 0 --passphrase
Note: In most instances your disk will be Disk 0, but to confirm that is correct run pgpwde --enum
This should allow you to restart the encryption process from the PGP Desktop interface.
Windows 7 64-bit
PGP Whole Disk Encryption 10.2.1 MP1