OK thanks. It looks like whatever caused the problem didn't make it into the system log before the reboot. To fix that we add an extra step:
1. Note the exact time and date of the freeze.
2. Press 'Alt + PrtSc + S' a couple of times. Or just waiting 30 seconds might also work.
3. Reboot.
4. Run: journalctl -b-1 > prevboot.txt
5. Attach the resulting text file here along with a note telling us the exact time and date of the freeze.
6. Check /var/crash for crash files.
OK thanks. It looks like whatever caused the problem didn't make it into the system log before the reboot. To fix that we add an extra step:
1. Note the exact time and date of the freeze.
2. Press 'Alt + PrtSc + S' a couple of times. Or just waiting 30 seconds might also work.
3. Reboot.
4. Run: journalctl -b-1 > prevboot.txt
5. Attach the resulting text file here along with a note telling us the exact time and date of the freeze.
6. Check /var/crash for crash files.