Just a comment in case it helps someone - I had MINT running fine, but then I installed a nice new VAC, and my boot just kept going in circles.
I wish I had consulted the FORUMS, but I re-copied my entire hard drive, then re-installed MINT; I got it to work but the screen resolution was AWFUL.
THEN I consulted the FORUMS and found part of the solution.
The card is a GIGABYTE, who had no drivers for me, but the CHIPSET is NVIDIA, and their website DID have drivers for all OS's, including LINUX.
However ..... they weren't doling out any, being Sunday and all, so I found an entry here which suggested the following, which DID WORK:-
sudo apt-add-repository ppa:xorg-edgers/ppa
sudo apt-get update
sudo apt-get install nvidia-current nvidia settings
This installs the latest NVIDIA driver, and you get your proper resolution, etc.
I then did some more fooling around, lost the way into ANYTHING, and instead of looking in here, I reloaded my entire hard drive again (I keep a good working system on a spare drive);
now I can't get in again - back to the loop-around on booting MINT, but I found a solution in here, I hope, will have to log out to try it.
SO, always look in here - do a search on the problem, it's amazing how many answers are in her, and so well organized (thank you!)