Kernel update gets stuck (Ubuntu 16.04, Kernel 4.4.0-22)
Solution 1:
Apparently, I have found the culprit. I reinstalled Ubuntu. Updated everything including the kernel. No problems up to now. Next, I started installing the applications I needed. The first one was Eset Nod32 Antivirus. After installing it, restarting, and logging in, Ubuntu froze. After booting into the recovery mode (the graphic mode) and unistalling Eset Nod32 Antivirus and restarting again, everything returned to normal. It seems as if there is a clash between the Linux kernel 4.4.0-22 and this antivirus, for some reason.