18.04 system with nvidia-driver-390 freezes when returning from console

[Jay S.]

Expected behaviour on exiting any console session:
1) the system keeps displaying the console until I manually select a different tty (ALT + F key)
2) I can log in on that tty (text or GUI) without any problem

Actual (and consistent) behaviour with nvidia-390 installed:
1) as soon as I enter "exit" on any console, I get kicked out and directed to GDM
2) GDM is completely frozen: the mouse pointer is stuck and most keyboard keys are dead
3) I can enter ALT + Print Screen, but that only makes the screen turn black
4) I need to push the reset button

One more detail: the bug is effectively triggered by the act of exiting - as long as all console sessions are kept open, the system behaves as expected.

I estimate that this problem is caused by the nvidia driver because:
a) I am seeing the same problem on a second computer that has different hardware but that is also using nvidia 390
b) the problem disappears as soon as I switch back to nouveau

Unfortunately, dmesg, Xorg.0.log and kern.log do not appear to offer any pointers that might shed more light on this bug.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Simon Junga (simonthechipmunk)]

I am also experiencing random system freezes with nvidia-390. Sometimes after just a few minutes, other times after hours of operation.

The graphics will start freezing for a few seconds at first. Keyboard and Mouse input starts lagging too. If I don't restart immediately at that point the freezes will continue to become longer and happen in shorter intervals until the GUI doesn't respond at all. If that happens I am also unable to switch to any tty and have to hard reset.
The system keeps running underneath though as audio calls continued working despite full graphics freeze.

This only happens with nvidia-390. I am unable to test nvidia-396 and above as support for Fermi was dropped.

The only thing noticeable are some NVRM messages in the syslog:

[ 3.629809] NVRM: loading NVIDIA UNIX x86_64 Kernel Module 390.77 Tue Jul 10 18:28:52 PDT 2018 (using threaded interrupts)
[ 47.315063] NVRM: GPU at PCI:0000:01:00: GPU-58038d8c-f108-4415-84ad-1b98a60c3344
[ 47.315089] NVRM: Xid (PCI:0000:01:00): 16, Head 00000001 Count 000009f8
[ 55.564951] NVRM: Xid (PCI:0000:01:00): 16, Head 00000001 Count 000009f9
[ 63.776270] NVRM: Xid (PCI:0000:01:00): 16, Head 00000001 Count 000009fa

These messages also appear randomly on screen when switching to a tty. Interestingly the messages are gone when I boot into recovery mode and then select 'resume normal boot'