I have a current version of VirtualBox 4.3.20, but after the latest Windows 7 update on Dec. 11th, 2014, it cannot open any virtual machine. First, it would not open the program at all. After a reboot, it would say:
Driver is probably stuck stopping/starting. Try 'sc.exe query vboxdrv' to get more information about its state. Rebooting may actually help. (rc=-101)
The log file says:
b28.146c: supR3HardenedVmProcessInit: Opening vboxdrv stub... b28.146c: Error opening VBoxDrvStub: STATUS_OBJECT_NAME_NOT_FOUND b28.146c: supR3HardenedWinReadErrorInfoDevice: NtCreateFile -> 0xc0000034 b28.146c: Error -101 in supR3HardenedWinReSpawn! (enmWhat=3) b28.146c: NtCreateFile(\Device\VBoxDrvStub) failed: 0xc0000034 STATUS_OBJECT_NAME_NOT_FOUND (0 retries)
I've tried installing an older version (4.3.18) as well, reinstalling the current version several times, rebooting, uninstalling antivirus software, but nothing helped.