Have you verified the integrity of the media you are booting from? Also, after downloading it is always best to check the MD5 is the same as the one given on the Mint LXDE download page.
If both of the above return positive results, please post back with more information about the hardware configuration of your computer.
A fact is a simple statement that everyone believes. It is innocent, unless found guilty. A hypothesis is a novel suggestion that no one wants to believe. It is guilty, until found effective.