Is this a boot of the computer or a virtual machine?
My first guess would be that it doesn't like the monitor--it may need some paramaters passed to it at boot.
What is the video controller (the command lspci entered in the terminal should reveal this information) and, if this is a desktop with a separate monitor, what are the make/model/specs of the monitor?
Mint 12 reached
end of life in April of this year. It might be a good idea to try something more recent; Mint 13 is a long-term support release supported until 2017 and Mint 15 is the newest mint of Mint.
If you post the output of the lspci command to LQ, please be sure to surround it with "code" tags, which become available when you click the "Go Advanced" button at the bottom of the quick reply window. That makes it much easier to read.