You can get that symptom when the hard drive is full. If you had an errant processing running that generated a zillion error messages, its credible that /var/log/messages is dozens (indeed hundreds) of gigabytes in size.
Login to run level 3, and check how much space is left in / (root) and /home.
That was the exact problem! Thanks so much oldcpu!! I logged in as root and ran kdirstat (very hand tool). There were a few massive log files in /var/log. I don’t know how they got to be so big… anyhoo, works now
I have emptied the files and checked them after a reboot. It has huge bzip2 backups of the files too. There is nothing out of the ordinary in them. It couldn’t connect to a printer and complains about that for a couple of pages The pk-backend file is full of stuff, don’t know what that’s trying to do. I expect is has something to do with automatic updates. I am considering adding a script to the kde startup folder to empty those files after boot. The computer is working perfectly so I don’t know where this is coming from.
That was the exact problem. I sent a job to the printer ages ago, and it was still trying to print it. I don’t even remember printing it! I changed the settings in Yast so that it discards jobs it can’t print. Hopefully, now it won’t do that in future.