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Windows 7: Windows Virtual PC: "Cannot attach the virtual hard disk ..." error

06 Sep 2012   #1

Windows 7 Enterprise 64 bit
Windows Virtual PC: "Cannot attach the virtual hard disk ..." error


Got a new Win7 Enterprise 64 bit machine, found that it did not come with virtual PC. Downloaded the critical patch Windows6.1-KB958559-x64-RefreshPkg.msu and installed it. Windows Virtual PC shows up in my Start Menu. Good so far. I go through the steps to create a virtual machine and use the option to 'use an existing vhd file' and when I click 'Create' I get the above pop-up message "Cannot attach the virtual hard disk to the virtual machine. Check values and try again". A factual message but completely useless as with all error messages from Microsoft. I have tried the following:
1. When I attach that vhd using Disk Management, it mounts in drive E:, I can see the files and browse the dirs in E:. In the Disk Management View, the drive shows up as 127 Gigs but 107 is unallocated space. The physical size of the vhd is only 25 Gigs
2. Others in my company were able to create the virtual machine with the same vhd, checked the byte size and timing, so nothing is wrong with the vhd file itself.
3. Tried to create after shutting down all virus protection including the Micorsoft antimalware protection service. No luck
4. Tried Vhd resize to resize the vhd to a smaller size (since it showed up in disk management as 127 Gigs, I thought maybe it was that size), but VHDResizer could not open the input file, gave an errors "Can only load fixed or dynamic drives"

What else can I do? Help!!! I have been at this for three days now. Thanks in advance.


My System SpecsSystem Spec
07 Sep 2012   #2

Windows 7 Enterprise 64 bit

I found out that I needed Windows XP Mode, So I installed that on my Win 7. That ones installs a VM during its install process which comes up looking good. Now when I try to connect my VHD to another hard disk, it gives me this error "One of the parent hard disks of c:\blah\blah .. appears to have been modified without using differencing disk."

Am I missing the base disk and the VHD I am trying to attach is just a differencing disk? Could that be my problem?

Thanks in advance,
My System SpecsSystem Spec
07 Sep 2012   #3

MS Windows 7 Ultimate SP1 64-bit

Got a new Windows 7 Enterprise 64 bit machine,
Talk to your IT Department.

My System SpecsSystem Spec
07 Sep 2012   #4

Windows 7 Enterprise 64 bit
IT Dept. questions?

Hey Karl, Thanks for the reply.
Do you know what I can ask the IT administrator? The strange thing is that other developers who followed the same steps were successful in creating a VM from the same VHD and I believe that they also have Win-7 Enterprise edition. I will however double check that.

thanks again,
My System SpecsSystem Spec

 Windows Virtual PC: "Cannot attach the virtual hard disk ..." error

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