With "a line at the bottom of the screen", do you mean the "task bar" of the Desk withtop Environment?
I am working with KDE and missing "fensterleiste" with the virtual placees "arbeitsflaeche" (task bar?) and the options above. The resolution of the screen was set automatically by software.
. . . i found following answer:
Invalid MIT-MAGIC-COOKIE-1 keyCan't open display :0