id summary reporter owner description type status component version resolution keywords cc guest host 5541 VMMR0.r0 expects C: drive to be the Windows System drive HexWizard "I was getting the VERR_NO_MEMORY (can't remember exactly, but something like this) on starting VMs. I am using the Windows version of VirtualBox. I was getting an ""unknown error"" loading VMMR0.r0. Since I could not think of any reason why VMMR0.ro should fail to load, I took a guess that because my system drive is E: and not C:, perhaps that was the problem. I ran the command subst C: E:\ and that gas definitely resolved the problem. Make VirtualBox more tolerant of non-C: system drives." defect closed VMM VirtualBox 3.0.12 obsolete Linux Windows