Be sure you don't run it off a read-only medium. How does your mounting look?

I mount it like in normal DOSBox. Maybe it's just that Vista security crap.

There is no Vista security crap.

Change the permissions on the folder within which MI2 resides.

Is there a way to circomvent this problem from within a Windows app itself using API's?

I was thinking round the folowing lines :

User starts a game in D.O.G.
D.O.G. detects the non-administrative or readonly permissions.
Asks the user to reset them.
D.O.G. resets the permissions.

Setting files to not readonly isn't the problem, but Vista's User Account Control is new to me.

Also for Vista I'll have to build in some new handling the option files, profiles and templates, they should then get stored under the users My Documents\D.O.G. folder, to avoid any security problems.

Erik.