http://telp.org/files/mm7/

The one you want is MM710-11.exe and it probably wouldn't hurt to read MM7 readme.txt. It cures a number of bugs, notably the Lich Jar bug, which prevents you promoting your sorcerer to lich if it strikes.

Mok's patch is an unofficial one which cures a lot of the problems that people find about running these games under WinXP and even Vista. (Most of the MM games were designed under Win95 and Win98.) It's not 100%, but it enables the game to run for over 90% of the people who have tried it, and so far as we are aware, it's as near bug-free as makes no difference. You can find a link to it at the link below, together with a description of what it does.

Enthusiast's post looks a good solution to your problem, but if you're using WinXP, then I would recommend the patches anyway.