Microsoft Windows 2008 R2 server running on HP Pavilion HPE H8-1210 with AMD FX-6100 processor (six core) or systems with AMD Processor series gives error message: "The virtual machine could not be started because the hypervisor is not running."
Booted the system into BIOS and checked for Virtualization and DEP options for ENABLE state.
Also changed the "nx" option to be "AlwaysOn" from BCD, and the hypervisor start option to "Auto".
This issue occurs because Windows Server 2008 R2 SP1 does not support the AVX feature on AMD processors or Windows Server 2008 R2 RTM does not support the AVX feature.
To resolve the issue request the hotfix download from the below Microsoft KB link.