This article describes an issue that might occur when third-party disk defragmenter software are used to defragment a PGP Whole Disk encrypted boot volume, and provides a recommendation for avoiding the issue.
After defragmenting a PGP Whole Disk encrypted boot volume with a third-party disk defragmenter (i.e. not the Microsoft Disk Defragmenter), the computer will no longer boot into Windows. Instead, the computer boots to the black "bootguard" screen (that displays bootguard in the top left corner).
During defragmentation, some third-party disk defragmenters move a critical PGP file (PGPWDE01) which is used during bootup of a computer protected by PGP Whole Disk Encryption.
The resolution to this issue is to exclude the PGP WDE file from Defragmentation. If your disk defragmenter allows you to exclude files from defragmentation, exclude the PGPWDE01 file from defragmentation. For reference, the PGPWDE01 is a hidden file located in the root of the encrypted volume. For example, if your encrypted boot volume is the C: drive, the PGPWDE01 file would be located at C:\PGPWDE01.