Comment 16 for bug 477256

That appears to have fixed the freezing. I used the system for over 3 hours, mainly web browsing. Previously, the limit was one hour, maximum, and often a lot less.

However, two odd things happened. Firstly, that the screen suddenly went blank for no apparent reason. Moving the mouse did not restore it but touching the touchpad did. This happened twice during the session. Secondly, the laptop did not shut down properly. The final message on the screen reads:

login: init: statd main process (2206) killed by KILL signal
init: statd main process ended, respawning
[11176.911297] System halted.

I had to pull out the plug to turn it off completely.