NScript Error CS1705 - Higher Version than Referenced Assembly

So I'm trying to run my first C# script with NScript to bulk delete some computers.  The script to do this has been discussed here and there's even a howto article here for 6.2.  However, anytime I run the script I get the following error .. I've even tried it on multiple boxes.  We're trying to run this on 7.5 with the latest updates and service packs installed.

* Compilation Error CS1705 in (0): Assembly 'Altiris.NS, Version=7.5.3300.0, Culture=neutral, PublicKeyToken=d516cb311cfb6e4f' uses 'Altiris.Common, Version=7.5.3300.0, Culture=neutral, PublicKeyToken=d516cb311cfb6e4f' which has a higher version than referenced assembly 'Altiris.Common, Version=7.5.3153.0, Culture=neutral, PublicKeyToken=d516cb311cfb6e4f'

Here's the relevant using statements in case it's relevant:

using Altiris.NS.ContextManagement;
using Altiris.NS.ItemManagement;
using Altiris.NS.Security;
using Altiris.NS.Logging;

So it looks like some of the internal assemblies have different versions but I can't see what I can do about that.  Any ideas?