IVssWriterCallback interface. hr = 0x80070005, Access is denied
The problem occurred when trying to take a Disk2VHD of the server to convert to a virtual server from physical. See below for event viewer logs.
The fix was to look in regedit under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\VSS\Providers
Expand each folder and look in the CLSID folder and the REG_SZ to the right for the corresponding GUID that is causing issues as per the event viewer logs.
Backup the Key and then rename and try the Disk2VHD again.