So my first thought there is that sounds a lot like what happens when you capture an Encrypted hard drive.
Assuming you aren't trying to capture an image with your encryption software installed, then the culprit is probably Microsoft BitLocker has enabled itself. I've had it do that on some systems automatically.
You may have to run the manage-bde -off command to get it to decrypt itself and then once it runs through decryption, BitLocker should be off at that point. Since I've had it do that to me before, I've stared actually disabling the BitLocker Drive Encryption Service on any PC I'm creating an image with. Obviously if you all do use BitLocker you probably don't want to go that far.