I ran into a weird issue today while performing a P2V migration.  The process would get to 40% and stop stating that the VSS Writer service stopped responding. 

Here is the error from the VMM Admin console job:

In the Application Log, the error showed up as follows:

In the System Log, the corresponding error was:

Is Services, the Volume Shadow Copy service was set to Started.

While troubleshooting the message from the Application Log, I was led to confirm that the “System Writer” was present as an association within the Volume Shadow Copy Service. 

To verify this, from the Command Prompt, type:

vssadmin list writers

“System Writer” was not there!  How to fix…?  Now I had to really dig.

The solution was posted here:

http://social.technet.microsoft.com/Forums/en/windowsbackup/thread/bb760434-de80-4cb6-ae9e-bd253e4b037c

It is quite the solution…  Here goes.  From and Administrator Command Prompt:

Takeown /f %windir%\winsxs\filemaps\* /a
icacls %windir%\winsxs\filemaps\*.* /grant "NT AUTHORITY\SYSTEM:(RX)"
icacls %windir%\winsxs\filemaps\*.* /grant "NT Service\trustedinstaller:(F)"
icacls %windir%\winsxs\filemaps\*.* /grant BUILTIN\Users:(RX)

- Stopped and started Cryptographic service

net stop cryptsvc
net start cryptsvc

Now, I verified again if “System Writer” was present.  It was!

I successfully completed my P2V migration after this issue was resolved.

Read the complete post at http://owsug.ca/blogs/brad/archive/2009/04/16/Unable-to-Perform-P2V-Migration-from-VMM-2008-_1320_-VSS-Writer-Stopped-Responding.aspx