We are running an application in win32/Vista, and sometimes, something has changed the permissions so we can not access them. We have a admin co-process that can change the permissions, but I am not sure what functions to call to insure that we have permission to access the files, from the non-admin user.

Thanks

Perhaps you might start by looking into GetFileSecurity Function. And from there on try to figure out the relevant parts of the Windows authorization.