Hi, my monitors refresh rate is 85hz and that's fine, how did you measure the refresh rate? Is the X server started (are you seeing a graphical interface or a command prompt)?
A "dos" prompt in Linux is called a command line, command prompt or a "shell". The most basic shell I am aware of is "sh" (short for shell). "bash" is short for "Bourne Again Shell", type "export" to see all your environment variables, in there you will see something like:
declare -x SHELL="/bin/bash"
declare -x HOSTNAME="shangrila"
declare -x TERM="xterm"
declare -x USER="tuttle"
declare -x USERNAME="tuttle"
plus lots of other variables. Type "man bash" and "info bash" (or "man sh") to learn more
The "dos" type window in graphical mode (or "X") is usually called a "terminal", a simple terminal for X is "xterm", this shows a bash command prompt or similar within its window.
"man xterm" and "info xterm" for more