I'm using Vista x64 with Virtual PC 2007.  I was trying to use the VhdResize.exe tool and got the following error dialog:

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Invalid Vhd file, please select another
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OK  
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Any ideas?

Two possibilties come to mind:

1. Are you sure the VHD file is not locked or in use while you are trying to access it via VhdResize? Make sure that VPC is not running and confirm that you can copy the file to another location on your drive. 
2. We've not done any testing of VHD's created with VPC 2007 on Vista x64. Do you have another machine you could test the VHD file on that is not x64? This will tell us if the problem is the VHD file itself or something related to Vista x64.

I have the exact same problem on _all_ my VHD files. Virtual PC is closed, I'm running Vista 32bit, the VHD files are not locked, and they were created some by VPC 2004 and some by VPC 2007. I got the same result on a newly created empty VHD file.

Can you send that emtpy VHD file directly to me please so I can take a look at it? davidb at vmtoolkit.com ..

 Also, We''ll do some more testing against VPC 2007.

I emailed the empty vhd file as requested.  I verified that nothing was using it and still was not able to resize it (same error).  As a test, I booted the virtual machine so that the vhd was in use, and I got a different error message.  There must either be something different about VPC 2007 files, or something weird with Vista.  Also, before you bother asking, I made sure that it didn't have anything to do with UAC (I made sure that I ran the resizer as administrator).

thermos:

I have the exact same problem on _all_ my VHD files. Virtual PC is closed, I'm running Vista 32bit, the VHD files are not locked, and they were created some by VPC 2004 and some by VPC 2007. I got the same result on a newly created empty VHD file.

Are you using compression on the File System (NTFS Compression)?  I am, and when I disabled it on the vhd file, it seemed to work.

It looks like NTFS Compression was causing a problem. We'll be posting an updated VhdResize in a bit.

Yes, I was using NTFS compression for all my vhd files. That's it! Thank you all.

I am also getting this message when trying to resize the .vhd file produced by Vista Complete PC Backup. As I understand it, Vista Backup only seems to restore to exactly the same partitions. I have a basic system using only 10GB of a 120GB disk I'd like to restore to a 80GB disk. When I noticed that the files on the DVD that Backup had produced were .vhd files, it struck me that VHDResize could be used. Any hope for a resize here?

Hi, I got the same message "Invalid VHD File". I copied my VPC from my Vista 32 machine to my XP machine.

Then I converted the VHD (16 Gb dynamic Server 2003 R2) to FIXED - it took hours. But after that I could resize it!