Pgpdisk
PGPDisk was a disk encryption solution from the PGP Corporation. It has since been rebranded as PGP Whole Disk Encryption.
It provides transparent whole disk encryption with Pre-Boot authentification for Windows. Also supports MacOS X 10.4 (non-boot disks only).
In 2007 an undocumented encryption bypass feature was found that allowed the drive to be accessed even without the boot-up password 1. The PGP Corporation said that the feature had been requested by enterprise users and was not a backdoor 2.