There seems to be a bug in Kubuntu's KDE Plasma that every time you close Google Chrome or reKonq, Plasma crashes.
A workaround is to use the 'Desktop' Workspace rather the 'Netbook.'
System Settings->Workspace Behavior->Workspace->Workspace Type, and choose Desktop.
Edit /etc/default/grub: Press Alt-F2 and enter this: gksu gedit /etc/default/grub.
Uncomment this line: #GRUB_GFXMODE=640x480 by removing '#', and change 640x480 to 1024x768 (Your monitor screen should support this by checking Grub2).
Open Terminal and enter this: $sudo update-initramfs -u