touchpad – The trackpad does not work (until it is reloaded) since the upgrade

I have a Lenovo Ultrabook (several years) on which I run
Ubuntu, with great success until now. There are some updates, the trackpad
did not respond at startup, but would be OK once I have reloaded the driver
(using modprobe -r psmouse; modprobe psmouse in a terminal). It seems to
a large number of error messages and warnings, mostly related to gnome,
in syslog. So there seems to be a configuration error; What should I do to diagnose / restore a normal state?

I can send syslog if needed, but the boot sequence is about 2000
lines. Some tips on what to look for would be a help.

Thank you