"Virtual PC was unable to commit changes" error message when you try to save changes to a virtual machine in Virtual PC 2004 (837340)

SYMPTOMS

If you select the option to save your changes when you try to shut down a virtual machine, you may receive the following error message:

Virtual PC was unable to commit changes made during this session. A likely cause of this problem is lack of free hard disk space on your physical computer. Your changes are not lost. However, the next time you start this virtual machine, you will be asked if you wish to keep the changes you have made or delete them.

CAUSE

This issue may occur when either of the following conditions is true:

You do not have sufficient space available on the physical hard disk to save the changes.
The Read-only setting is selected on the virtual hard disk (VHD) file.

RESOLUTION

To resolve this issue, follow these steps:

Make sure that there is sufficient disk space available to commit the changes. If the drive that contains the virtual machine does not have sufficient free disk space, delete unnecessary files, or move the VHD file to another drive.
Make sure that the VHD file is not set to Read-only. To do this, follow these steps:
1. Click Start, point to All Programs, point to Accessories, and then click Windows Explorer.
2. Locate the drive and the folder where the VHD file is stored.
3. Right-click the VHD file, and then click Properties.
4. Make sure that the Read-only setting is cleared.

When you restart the virtual machine, you are prompted to either commit or delete changes to the VHD file.