A. I'm out of ideas. The Windows 7 guest crashes, if I try to access the shared folder /mnt/winos7/winOS_2/ with this content: [rocketmouse@archlinux ~]$ ls -hAl /mnt/winos7/winOS_2/ total 417M -rw-r--r-- 1 rocketmouse rocketmouse 155M Jul 28 17:09 iCloudSetup.exe -rw-r--r-- 1 rocketmouse rocketmouse 263M Jul 28 17:12 iTunes64Setup.exe -rw-r--r-- 1 rocketmouse rocketmouse 0 Jul 28 17:40 test.txt [rocketmouse@archlinux ~]$ grep VERR_VM_DRIVER_NOT_ACCESSIBLE .VirtualBox/VBoxSVC.log 00:00:00.117543 nspr-2 Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE 00:00:00.561476 nspr-4 Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE The Windows 7 guest can open the shared folder without any issue, if this is the content: [rocketmouse@archlinux ~]$ ls -hAl /mnt/winos7/winOS_2/ total 0 -rw-r--r-- 1 rocketmouse rocketmouse 0 Jul 28 17:40 test.txt [rocketmouse@archlinux ~]$ grep VERR_VM_DRIVER_NOT_ACCESSIBLE .VirtualBox/VBoxSVC.log 00:00:00.116380 nspr-2 Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE 00:00:00.561547 nspr-3 Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE In both cases the log shows "VERR_VM_DRIVER_NOT_ACCESSIBLE". Still ok, but a fishy log: [rocketmouse@archlinux ~]$ ls -hAl /mnt/winos7/winOS_2/ total 4.0K drwxr-xr-x 11 rocketmouse rocketmouse 4.0K Jul 19 03:58 auriapro-2019-jul-19-TESTCOPY -rw-r--r-- 1 rocketmouse rocketmouse 0 Jul 28 17:40 test.txt [rocketmouse@archlinux ~]$ grep VERR_VM_DRIVER_NOT_ACCESSIBLE .VirtualBox/VBoxSVC.log 00:00:00.131207 nspr-2 Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE 00:00:00.888320 nspr-3 Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE Still ok: [rocketmouse@archlinux ~]$ ls -hAl /mnt/winos7/winOS_2/ total 32M drwxr-xr-x 11 rocketmouse rocketmouse 4.0K Jul 19 03:58 auriapro-2019-jul-19-TESTCOPY -rw-r--r-- 1 rocketmouse rocketmouse 32M Jul 28 18:03 GR-55FloorBoard_Setup.exe -rw-r--r-- 1 rocketmouse rocketmouse 0 Jul 28 17:40 test.txt Crash: [rocketmouse@archlinux ~]$ ls -hAl /mnt/winos7/winOS_2/ total 295M drwxr-xr-x 11 rocketmouse rocketmouse 4.0K Jul 19 03:58 auriapro-2019-jul-19-TESTCOPY -rw-r--r-- 1 rocketmouse rocketmouse 32M Jul 28 18:03 GR-55FloorBoard_Setup.exe -rw-r--r-- 1 rocketmouse rocketmouse 263M Jul 28 17:12 iTunes64Setup.exe -rw-r--r-- 1 rocketmouse rocketmouse 0 Jul 28 17:40 test.txt Just in case I removed anti virus software from the guest install, but it still crashes with the iTunes64Setup.exe in the shared folder. The only change for the guest from working to broken was an update of the anti virus software's data base. IIRC the original log file from the backup doesn't contain "Failed to open "/dev/vboxdrvu", errno=13, rc=VERR_VM_DRIVER_NOT_ACCESSIBLE", so I still suspect the host, not the guest. I'll restore from the backup later.