You experience problems when you try to mount VHD files by using the Vhdmount.exe tool after you apply update 948515 in Virtual Server 2005 R2 SP1

You apply update 948515 on a computer that is running Microsoft Virtual Server 2005 R2 Service Pack 1 (SP1). After you do this, you experience problems when you try to mount Virtual Hard Disk (VHD) files by using the Vhdmount.exe tool.

For example, if you run the vhdmount /m vhd file command or the vhdmount /p vhd file command, you may receive the following error message:

This issue occurs because the Vhdstor.sys driver is not successfully upgraded to version 1.1.623.0 after you install update 948515.

To resolve this issue, you must manually upgrade the VHDMount driver. To do this, follow these steps:

1. Restart the computer.
   
   Note You must do this before you update the driver because the Microsoft Virtual Server Storage Devices driver must be unloaded before it is updated.
2. Click Start
   , click Run, type devmgmt.msc, and then press ENTER.
   
   
   If you are prompted for an administrator password or for confirmation, type the password, or click Continue.
3. Right-click Microsoft Virtual Storage Device, and then click Update Driver Software.
4. Click Browse my computer for driver software, and then click Let me pick from a list of device drivers on my computer.
5. Click Have Disk, and then click Browse.
6. Locate the Virtual Server installation folder, and then open the VHDMount directory.
7. Select the Vhdstor.inf file, and then install the driver.

For more information about update 948515, click the following article number to view the article in the Microsoft Knowledge Base: After you install update 948515, the driver version for the Microsoft Virtual Server Storage Device is still displayed in the Device Manager console as the earlier version of the driver (1.1.594.0) instead of version 1.1.623.0.

To view the driver version, follow these steps:

1. Click Start
   , click Run, type devmgmt.msc, and then press ENTER.
   
   
   If you are prompted for an administrator password or for confirmation, type the password, or click Continue.
2. Right-click Microsoft Virtual Storage Device, and then click Properties.
3. Click the Driver tab, and then examine the driver version.