SQL Permission problem.

Hi all,

I need an advice about creating a login for Navision use on SQL 2005. I think Navision requires the login to be a member of securityadmin server role (otherwise it's impossible for a user mapped to the login to change its password within Navision). But securityadmin is a over-privileged role for only a Navision user. Denying "alter any login" permission in server-wide produces the same result as denying securityadmin role. What I'm afraid of is that the over-privileged login can log on the server by using Management Studio and change passwords of others. The only way I could figure out was to deny Alter permission for every other login. But this is a very tedious job because every login must be negated for all other logins except itself.

I'm absolutely sure that I do something wrong . Readjustments will be greatly appreciated!