On a machine with two drives, both of which are encrypted with Encryption Desktop drive encryption, you are prompted for credentials in order to access the secondary drive.
The boot drive and the secondary drive are in different Disk Groups and therefore have separate passphrase users associated with them.
One reason this will occur is if the secondary drive is detected by Encryption Desktop as Removable Media rather than a Fixed Disk.
Check whether Encryption Desktop has classified the secondary drive as Removable Media and/or whether the secondary drive is in a different Disk Group to the boot drive:
Before the secondary drive can be added to the same Disk Group as the boot drive, it needs to be decrypted. Click on the drive and then click on the Decrypt button. You will be prompted for the passphrase of one of the users in the User Access list of the secondary disk. Note that the account will need appropriate permissions to decrypt the drive. These permissions are set in Consumer Policy in Encryption Management Server for managed clients.
After the secondary drive is decrypted, it is worth investigating whether Windows can be configured to treat the drive as fixed rather than removable. See the suggestions in this article for example.
If the secondary drive is detected as a Fixed Disk by Encryption Desktop, when you encrypt it you will need only supply a valid user passphrase for the boot drive. The secondary drive will automatically be added to the same Disk Group as the boot drive and the same users will have access to it.
If Encryption Desktop still detects the secondary drive as removable, you will need to add it to the same Disk Group as the boot drive before you encrypt. To do this:
"C:\Program Files (x86)\PGP Corporation\PGP Desktop"on a 64-bit system or
"C:\Program Files\PGP Corporation\PGP Desktop"on a 32-bit system.
pgpwde --add-disk --base 0 --disk 1 --interactive
pgpwde --encrypt -d 1 --interactive