Windows 7 and MS-DOS boot + Linux Mint - DOS overriden by GRUB4DOS?

Hi!

I installed MS-DOS, then Windows 7 and by EasyBCD created dual boot menu - Win 7 and MS-DOS.
Then I installed Commodore OS Vision 1.3 (Linux Mint based), which automatic adds Windows boot option to GRUB boot menu.
All was working correctly, MS-DOS, Win7 and Commodore OS... but yesterday I tried to boot to MS-DOS.
Failure - it started GRUB4DOS and by TAB key are shown all available commands, but no one syntax I understand.
How was MS-DOS boot overriden? I can boot to MS-DOS only by diskette and then run AUTOEXEC.BAT on HDD.
How to fix MS-DOS boot?
I mean possible fix is by EasyBCD, it's for me much easier than play a game with GRUB... but how to add there Linux Mint (Commodore OS)?



Thank you for each help.
Miro

Maybe I understand not correctly.
My problem is not in adding OS to GRUB.
I have there also Windows 7 option, which when is selected I can choose between Windows 7 and MS-DOS - it's classic boot of Windows 7.
Problem is when I select MS-DOS it forces GRUB4DOS...
Long time it was working - all three OSes - Windows, MS-DOS and Linux, but after longer time I tried to boot MS-DOS... and problem began.
Miro

Hi Samuria,
I need fix booting to DOS - it was possible by Windows bootloader, but later was booting to DOS replaced by GRUB4DOS - not after installing Linux, it happened later and really don't know why and how it happened. Or is possible to add DOS to GRUB? Then after Win7 choice it can boot to Win7 directly - I mean I know remove DOS from Windows bootloader, and boot to DOS directly from GRUB...
Miro

Again it needs correction:
After installing Linux booting to DOS was possible by Windows 7 menu after Win7 selection. All three OSes worked correctly. But later (unknown reason and time) when I selected in Win7 bootloader DOS item, it forced to GRUB4DOS...
Miro