I notice something that may be important related to this (I had the same problem).
when I did an "apt-get update; apt-get upgrade" and doing it multiples times to upgrade, I always got the message that package "linux-generic linux-headers-generic linux-image-generic" where kept back. but doing "apt-get dist-upgrade system-services" updated them.
I notice something that may be important related to this (I had the same problem).
when I did an "apt-get update; apt-get upgrade" and doing it multiples times to upgrade, I always got the message that package "linux-generic linux-headers- generic linux-image- generic" where kept back. but doing "apt-get dist-upgrade system-services" updated them.