Sadly, I have no way of reproducing the problem: it comes and goes after a reboot, I can't reproduce it. But I have updated the BIOS as suggested. Worked fine for a while (as it did before) But it has happened again. This time not only where there characters missing on other software but it also showed strange character substitution.
$ sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date U33Jc.213 01/24/2011 -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1594554 Title: Some letters are missing in thunderbird at least To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1594554/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp