VMware Fusion Converter VSS issues

VMware is simultaneously both very nice and very frustrating.

I have a 4.5 year old laptop (Sony Vaio Z) running Windows 7 Ultimate, and decided to virtualize it.  Great idea!

VMware Fusion comes with a physical-to-virtual converter.  Piece of cake!

But every time I try, I get the big bad message :

"An Error Occurred

"The VSS snapshots cannot be stored because there is not enough space on the source volumes or because the source machine does not have any NTFS volumes.  Error code: 2147754783 (0x8004231F)."

Thanks VMware!

So here are some of the things I tried that have helped not a bit :

• I spent a long time clearing stuff off the 147GB C: drive until there was over 10% of the drive free.  Still kept complaining.
• I disabled my R: drive RAM disk.  It was an NTFS drive, but just in case somehow it was causing trouble, I completely turned off the RAM drive system.  (Note that I had P2V'ed a Windows 8.1 machine with a RAM disk successfully, using the same tool, so this never seemed likely to be the problem.)
• I suspended BitLocker in case that was somehow interfering (although note that I had P2V'ed a Windows 8.1 machine with BitLocker successfully, using the same tool, so this also seemed unlikely to cause the problem).
• I adjusted a MaxTokenSize registry setting.
• I completely disabled "previous versions".
• I fully enabled "previous versions" (both for my files and for operating system files - i.e. the highest level) and allocated it 10% of the available space.
• I deleted all existing previous versions.  If you're doing the maths, this means there are roughly 14GB available and allocated to VSS.  So space shortage is not the problem here!
• I confirmed that there are no other mounted drive letters - I removed all USB sticks and external drives.
• I confirmed that there are no unmounted volumes on the one internal drive, other than a 15MB one that appears to be a boot volume and is nearly entirely full but I doubt there's anything much I can do about it.
• I created a new administrative user and tried using that account instead of my normal administrative account when doing the physical-to-virtual conversion.
• I did a full checkdisk scan on a reboot - i.e. whilst the C: drive was not in use.
• I rebooted the Mac OS/X computer that was on the receiving end of the process.
• And of course, throughout the above I rebooted the Windows laptop many times over.
• I discovered a "bakk" (yes - double 'k') entry in HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\ProfileList as discussed here, deleted it and rebooted, and same problem (although strangely & interestingly, laptop shutdown and boot times were much improved, or so it seemed to my subjective impression!).
• I also verified that the other SIDs in that registry key were all valid (using psgetsid from PSTools as described here).

The VSS service was creating error log entries claiming that there is an "Unexpected error calling routine ConvertStringSidToSid" (0x80070539).  This is what led me to wonder if checkdisk might be needed - but that didn't help - and is also what led me to the MaxTokenSize trick linked above, which also didn't help.  However, after deleting that "*.bakk" registry entry, the VSS service has produced no more error messages - yet the error message from the VMware Converter remains the same, blaming VSS.

It's not inspiring that multiple other people online seem to have given up on this one.  (e.g.)

I also report with disappointment that this was not my first unfavourable experience with this supposedly easy physical-to-virtual conversion tool.  About a week ago I converted a Surface Pro 2 (Windows 8.1) physical to virtual prior to sending it in for servicing.  I also had a lot of trouble then, although finally managed to get it to work.  Two bad experiences out of two attempts.  Relatively useless documentation.  Sadly, this is my experience of VMware so far : It is awesome when it works, and an extreme pain when it doesn't, which is far too often.