What exactly do you see at the "command prompt"?
Did you select to boot automatically or require a password for login?
Did you select to install the Mint bootloader to the master boot record?
Can you post some information on your hardware? How old? graphics card? memory?
Did the CD work before installing?
I would suggest going to the site below and downloading and running the bootinfoscript. This will produce a results.txt file which you can post here to get help. It will give detailed information on your partitions/drives and boot files.