Incorrect KDE Ubuntu Shut down. Only browser was opened after startup
Solution 1:
Okay, there seems to be multiple problems. First - the plasma-Desktop: it seems the system still works and apps can run. Maybe your have a broken Plasma-config (located in ~/.config). You can test this by just renaming the folder and restart - you can use the virtual terminal (Ctrl+Alt+F2).
mv ~/.config ~/.config_bck
If you get your Plasma-Desktop back, you're fine (okay, you have to reconfigure the stuff, but hey - i think thats not that bad at all... Also you can write back the config-files step-by-step from ~/.config_bck to ~/.config)
Second: The Kernel-Log says, that you have an mask-error with your root-pcie-device. Did you really restarted the system or did you just done a soft-reboot? My advice: Unplug your pc - Push the power-button twice, replug and start over. Maybe you have also activated some virtualization-stuff in Bios (Intel VT or AMD-V). Disable it, if you dont need them.
Sry if there is bad grammer... I'm still german :-)