There are a number of ways to go about doing this. I would suggest this.
Go to the Supergrub site and download the iso and burn it. This is a handy disk to have around. You can use it to boot into almost any system. Don't be tempted to try to "fix" the system with this disk. Just use it to boot with.
Use Supergrub to boot into your Mint 4 install. Open a terminal and type:
This assumes that your Mint 4 /boot is on sda2 and you are booting from the first hard drive, which you probably are.
Then open gedit by typing in a terminal:
Navigate to a file called /etc/fstab and open it. Find the line for your ntfs windows partition and see what it is called. It will probably be sda1. Just below that you will see a string of letters/numbers. This is a UUID number. It is wrong.
Open a terminal and type:
sudo vol_id -u /dev/sda1
It will return a string of letters/numbers. Replace the wrong UUID in /etc/fstab with correct one you just calculated.
Save this file and quit everything and reboot. It should work now.