I was troubleshooting some Windows hangs on my Desktop system running Windows 8 and enabled driver verifier. Today when I tried to start VirtualBox it failed with this error message.

Failed to load VMMR0.r0 (VERR_LDR_MISMATCH_NATIVE)

Most of the online forums were asking to reinstall VirtualBox to fix the issue. But one of the thread mentioned that it was being caused by Windows Driver Verifier. I disabled it, restarted Windows and VirtualBox worked like a charm. Didn’t have time to do more research as i quickly wanted to test something. May be we can skip some particular stuff from Driver Verifier and VirutalBox can then work.