I'm using 12.04LTS. Last week I upgraded to the latest (at the time) kernel, 126.96.36.199 and my display system became completely unusable. I have two displays on an Nvidia video adapter. I suspect the ABI changes in this kernel made the Nvidia proprietary drivers not work. I could only get my system back by a fresh install. (With my work directories all on another hard drive, I can re-install and be running again in about an hour). I'm now at kernel 188.8.131.52 after my initial upgrade. The updater indicates it needs to upgrade to .48, but I know there are interim kernels. My question is about the apt-get upgrade process with kernels. Does this always only advance one kernel? That seems to be the case, but don't know if there are exceptions. I'd like to do my upgrades and get to 184.108.40.206 which is the last one that worked for me. Then wait for nvidia and/or kernel updates that allow me to go further.
Welcome to AskUbuntu.