I have recently (the other day) reinstalled a fresh copy of UM 16.04 LTS 64 bit.
However, a novel issue has arisen.
When the system is booting up, just prior to the login screen, it locks up. However, if I switch off my monitor, the boot-up/login resumes. If I wait a few seconds and then switch the monitor back on, it is at the login screen and I am able to enter my password and click the login button. But, it then completely freezes again. Once more, if I switch off the monitor, the login will resume and when I switch the monitor back on again, I am now in the session and all works as it should.
But, when I go to log out, I have the same problem in reverse, more or less. That is to say, after invoking the logout, the screen drops to the usual console and displays the logging off processes, but then locks up a fews seconds in. The only way to unlock it is to switch off the monitor, at which point the logging off will complete.
I have never experienced this problem before and so am very interested as to what is causing it.
I am guessing it is a GPU/monitor issue and so, for clarity, the GPU I am using is Radeon R7 200 and the “monitor” I am using is actually a bog standard supermarket LCD TV with an HDMI input
I should also note, this issue was not present when I first installed. However, since then, I have installed the Ubuntu studio meta package and have implemented all updates/upgrades. Somewhere in that process is when the problem began. But, I cannot say precisely where.
Any advice/help gratefully received.