I was recently working on a issue where several production servers fail to  boot, after some extended troubleshooting it turn out to be a simple and easy resolution.

Many customer when dealing with 7Bs opt to rebuild but in this particular case that can be avoided.

It’s quite common that 7Bs are triggered by 3^rd party filter drivers, but this driver is new in the “suspects List” so be aware!

Issue:

After Installing/upgrading EMC Networker version 8.1.1 windows fails to boot - stop error 7B "inaccessible boot device"

Cause:

The issue is caused by EMC nsrbbbwi.sys filter driver which is hooking up to VSS and Storage volumes.

Resolution:

To resolve this issue, boot from WinRE, run regedit, load the system hive from system drive C:\windows\system32\config

Note: depending on the disk configuration and existence of reserved partition the drive letter for the system drive might be different.

Delete the upperfilters “nsrbbbwi” entries from these two keys.

ControlSet001\Control\Class\{533C5B84-EC70-11D2-9505-00C04F79DEAF}

ControlSet001\Control\Class\{71A27CDD-812A-11D0-BEC7-08002BE2092F}

Note: delete ONLY the uppfilter entry not the entire key.

Exit Regedit and Restart.

EMC has confirmed this is an issue introduced by the EMC Networker and that nsrbbwi.sys is no longer required.

If you have installed/upgraded EMC Networker but didn´t reboot then you can validate/delete these values directly from regedit.

Additional you can also cmd line/script  "reg.exe"

However this is not practical  if you want to establish the same settings for several machines.

In  Pre-Win 8, apps could set the default handler for a file type/protocol by manipulating the registry, this means you could easily have a script or a group policy manipulating the registry.
For example  for Mailto protocol you just needed to change the “default” value under HKEY_CLASSES_ROOT\mailto\shell\open\command

However In Win 8, the registry changes are verified by a hash (unique per user and app)  that detects tampering by apps. In the absence of a valid hash, we ignore the default in the registry.
HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\URLAssociations\MAILTO\UserChoice

Solution:
Microsoft  have  introduced a new GP mechanism for declaring these defaults in Win 8 to accommodate this type of scenario. The basic idea is to have an xml file that maps programs to the file type/protocol that they should be the default for.
First you create your XML file or export it from a machine using DISM (https://technet.microsoft.com/en-us/library/hh825038.aspx):

Then you use the  new Windows 8  group policy that enables you to set the association for file types and protocols:
Computer configuration\administrative templates Windows Components\File Explorer\ Set a default associations configuration file
<HKLM\Software\Policies\Microsoft\Windows\System!DefaultAssociationsConfiguration>
This policy specifies the path for the XML  file that can be either stored locally or on a network location.

 
Note : using DISM to import the XML  is not enough you still have to link it to the GPO.

Note2:Bear in mind that the machine needs to be domain-joined and the associations are applied at logon time!

FAQ:
Q:I've tried this to set the mailto protocol association to outlook. But DISM doesn't show the value in the export. Anybody know a fix for that?
A:if the Program/Extension/Protocol is not present in the XML export, then you  need to first manual enable the association  Before running DISM. 

Q:Does this process work without having to re image a machine?
A: Yes.