VMs won't start hanging with msg "Starting virtual machine - 0%"

[eugenesany]

(Also reported at ​https://bugs.launchpad.net/ubuntu/+source/virtualbox/+bug/1562397) On fresh Ubuntu 16.04 with VirtualBox 5.0.16 virtual machines won't start hanging with msg box "Starting virtual machine - 0%". The issues is not persistent but once it happens to specific virtual machine, that machine won't start anymore.

Observations:

• Affects both build from Xenial repo and Oracle package
• Both Linux and Windows virtual machines affected but Windows machines cause heavy I/O until all VirtualBox processes are killed
• Tested on Skylake and Sandybridge machines
• Downgrading to 5.0.14 doesn't help
• Removing extensions pack doesn't help
• libvirt@qemu-kvm is working ok
• Nothing useful in log but attached anyway
• No suspicious massages in dmesg

Might be related to system being installed on BTRFS.

[eugenesany]

VM Log

[eugenesany]

Seems like the issue is the same issue reported in https://www.virtualbox.org/ticket/11862.

Unfortunately, original report left unresolved for long time and that's wrong since now days BTRFS is becoming mainstream. Something must be done and maybe new bug report will draw the attention this issue deserves.