I've been trying to figure out how to, but iolo did not make how to enable/disable System Shield very intuitive, which is very frustrating. Part of me doesn't want to uninstall my entire System Mechanic Professional, but that may be what I need to do to get this to work. *le sigh*
As Shia_luck suggests, try installing into a folder outside of Program Files
, such as c:\games. A lot easier that way :)
Otherwise, you can usually use MSCONFIG to stop particular programs loading : http://netsquirrel.com/msconfig/msconfig_win7.html
Under the Startup tab look for anything that might be applicable eg 'Iolo', 'System Mechanic', 'Active care', etc and uncheck the box(es).
Click Apply and OK, then reboot - make sure you're not connected to the internet when you
do. If there's no Mechanic running in the background, try installing the game again.
When you're finished (hopefully with NWN installed), reenable the appropriate box(es) in MSCONFIG and reboot.