The SQLExpress database will be intsalled on a share of a Windows7 machine
SQL is not Access. It's not a file-based database that sits on a share. It's a service that other machines connect to.
With the SQL Service running on a Windows 7 machine, anyone who has administrative access to that Windows 7 machine can do what they like to your database (and that includes dropping it, uninstalling the service, etc).
You need to lock that machine down and treat it like a server if it's serving data.
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