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I'm trying to set up a Virtual PC of vhd backup of an old Windows Vista install in Windows 7, using the optional "Windows Virtual PC" update (now in RC).

Unfortunately, I attempt to set up a virtual PC using the vhd as the source, and I receive the error message:

Cannot attach the virtual hard disk to the virtual machine. Check the values provided and try again.

To top it off, I can't find a way to manually change the values - e.g. establish a new virtual machine via the command line, or a more complex GUI.

Any ideas?

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You can only attach IDE VHDs via Windows Virtual PC. Your drive is limited to ~128 GB. You need to shrink the VHD size to attach it.

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Might you have any reference for this? This seems like a very poor design decision if true. – Ian Boyd Oct 30 '09 at 15:54
The limit is actually 137GB. The reason is the ATA barrier: I have seen the same on a Virtual PC features page of Microsoft, but can't find back the link (and Bing, as always, is so lousy with this...). – Abel Jul 19 '10 at 18:45
Virtual PC was meant for development and testing, or limited usage. It has an artificial HD Size limit. Virtual Server and Hyper-V have different limits however. – Chris S Jul 19 '10 at 19:24

Sounds like while your VHD file is less than the 128GB limit, the actual "max size" of the disk is probably over that because the original drive it came from was. That's the size Virtual PC is looking at, not the actual size of the VHD file.

So, you basically need to shrink the size of the volume contained in the VHD. You can do this by attaching the VHD in disk management under computer management on the physical computer. You may need to defragment the disk first so that enough empty space is available to remove. You can do this as if it was a normal disk (after attaching it).

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Some of your answers have been about the 128GiB / 137GB limit. if you pass that limit, there's little that can help you (while perhaps the Windows 7 Virtual PC may have more possibilities). However, there's more to it, it seems. This post explains the caveats and dos/donts of using a backup VHD.

In addition, while this KB post is of an older version of VPC, it might still apply in parts to VPC 2007. Give it a look.

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Are you using Kaspersky Anti-Virus, by chance? Googling that error message shows a lot of people having the same problem, which is resolved by turning off Kaspersky.

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Nah, checked for that first thing. I figured it out - you can only attach IDE VHDs via Windows Virtual PC (some upgrade!), so your drive is limited to ~128 GB. You need to shrink the VHD size to attach it. – user16246 Aug 21 '09 at 0:49
@Michael, May I suggest you post you your comment as an answer so that you can set it as 'accepted', so others can find it if they have the same problem? – Mark Henderson Aug 24 '09 at 23:03

Best bet to shrink the volume is to attach it to a HyperV host and compact it, resize it, or use Virtual Box to boot it instead of Virtual PC. We recently ran into a similar issue backing up workstations prior to a move to Windows 7 using disk2vhd.

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