Following up, I have made the following changes to my system recently. Two occurred within the week prior to this problem appearing, but not immediately before to my knowledge, so it's not certain that any of them are applicable. They are listed in order of first use.
- Added a 4K monitor on HDMI a month ago). - Switched from Intel graphics to NVidia. - Added a bluetooth speaker system, which took a bit of messing about with the GUI bluetooth devices panel before it finally decided to work. - Began using a bluetooth headset with my phone but not the laptop. Operating system is Mate 18.04. Kernel is 4.17.11-041711-generic Message in kern.log is as follows. When the failure happens there are three lines of text on the screen. The third line is different but I don't recall what it was, and it is not shown in kern.log. Jul 14 17:34:56 Hebegb kernel: [ 6618.034362] hid-sensor-hub 001F:8086:22D8.0005: timeout waiting for response from ISHTP device Jul 14 17:34:56 Hebegb kernel: [ 6618.034391] hid-sensor-hub 001F:8086:22D8.0004: timeout waiting for response from ISHTP device -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1807406 Title: hid-sensor-hub 001F:8086:22D8.0003: timeout waiting for response from ISHTP device To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1807406/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs