Ubuntu 17.10 guest freezes when restoring guest windows

[DMeganoski]

Okay, so this is driving me nuts. Running VB 5.1.30 on a windows 7 host with a Ubuntu 17.10 (desktop) guest OS.

I installed the guest additions without issue, though I read here ​https://forums.virtualbox.org/viewtopic.php?f=6&t=85186 that Ubuntu comes with a set of guest additions installed by default that may cause issues, not sure if that's relevant.

Everything works fine (for the most part) but when I enable 3d acceleration (host has a gtx1070) it runs smoothly... until I 'restore' (un-maximize) a window within the guest.

Then the machine freezes (any actions take 3-10 seconds for a response) and begins consuming as much as 15-17% of my (i7) cpu and even slowly getting the original window to close in the guest does not restore it's usability or reduce it's cpu consumption.

Disabling 3d acceleration allows the machine to run stably however it's not very smooth comparably, and simulating both my 2560x1440 monitors makes the machine so sluggish it's not usable.

Any hints to why this would be happening and how to fix it would be much appreciated.

[DMeganoski]

Log after reproducing

[Socratis]

Please read the Note (in red letters) in the Downloads section: https://www.virtualbox.org/wiki/Downloads