The error comes up when starting the virtual machine:
Unable to connect to Hard Disk
Possible Reasons & Resolution
- Mounted virtual Hard Drive
Make sure you didn't mount your virtual drive to the Mac desktop. You could do it by right-clicking on PVM bundle which is usually located at your Home folder/Parallels and choosing Open With --> Parallels Mounter. If that's the case, please unmount it by right-clicking on the drive on the desktop and selecting Eject.
!(http://kb.parallels.com/Attachments/18826/Images/Screen Shot 2012-02-12 at 23.32.31.png)
Failed operation with the virtual Hard Drive Such operations with virtual hard drive like compressing, any actions with the snapshots or resizing the hard drive should never be interrupted. If one of these operations was interrupted in your case and you get the error message "Unable to connect to Hard Disk", please try to restart your Mac and restore your virtual machine from the backup (in case you use Time Machine or other utility for backing up data). If your virtual machine still doesn't start, run the chkdsk and see if it helps.
Mac force shutdown with Parallels Desktop virtual machine being on Shutting down the Mac when one of your Parallels Desktop virtual machines is running can be of great harm for the virtual drive. If restarting doesn't help, try to restore your virtual machine from the backup.
If all of the steps above didn't help, most probably your virtual machine is corrupted. You may want to try to retrieve your data by mounting your virtual drive by Parallels Mounter and creating a new virtual machine.