This Knowledgebase article describes how to troubleshoot System Crash (Stop Error) 0x7B, Inaccessible Boot Device errors and when installing Neverfail Heartbeat on Windows Server 2008 and 2008 R2 with different disk subsystems.
When Neverfail Heartbeat is restarted following a restore on the Secondary (or Tertiary) server, the Secondary (or Tertiary) server stops with the following error message:
System Crash (Stop Error) 0x7B, Inaccessible Boot Device
This error occurs when the system disks on the Primary and the Secondary (or Tertiary) servers have different disk/RAID controllers.
This problem can be anticipated and prevented by renaming the driver file for the Secondary (or Tertiary) server boot disk controller to the same name as the Primary boot disk controller before restarting the Secondary (or Tertiary) server.
If a restart is performed without renaming the driver files for the server boot disk controller on the Secondary (or Tertiary), a system crash (BSOD) will occur. To restart the server, use an ERD (Emergency Repair Disk) or similar utility and rename the drivers as described above.
Neverfail Heartbeat, all versions
Microsoft Support article — Error messages when you try to gain access to an NTFS volume