INT 21 - LANtastic - DISABLE ACCOUNT
        AX = 5F86h
        ES:DI -> ASCIZ machine name and password in form "\\machine\password"
Return: CF clear if successful
        CF set on error
            AX = error code
Note:   must be logged into the named machine and concurrent logins set to 1
          by NET_MGR.  Requires system manager to re-enable account.