Important notice: If you use Parallels Desktop 7 or 8 check this article: 112140 An error occurred while accessing the Hard Disk.
On Windows startup you get the "Unable to access Hard Disk 1: Error ID: Input/output error":
When you are trying to make a copy of the .pvm file of your virtual machine you get the copy error "Error code -36".
The sector of Hard Drive Disk where the data of the virtual machine is stored was corrupted. The problem is on the hardware level.
If you have a Time Machine backup copy on an external hard drive, try to restore the virtual machine from the backup. If you do not have a backup, the virtual machine is lost, but you can still retrieve the data from your virtual hard drive:
1. Create a new virtual machine, install Windows there.
2. In the configuration of the new virtual machine go to the configuration editor, add the hard drive image of the corrupted virtual machine as a second drive.
After the start of the new virtual machine, an additional hard drive image will appear as an additional labeled disk.
Copy all the necessary data to disk C, untie the hard drive image in the configuration of the new virtual machine, and delete the .pvm bundle of the corrupted virtual machine.