Make Sure you Have Dot NET Installed
If you’re using Windows 7 or 8 this check is unnecessary. If using Windows XP see here.
Make Sure you Have ArcGIS10.1 Service Pack 1 Installed
Everything should work without Service Pack 1 installed, but we do recommend you update to this Service Pack. This video shows you how to check for the Service Pack (checks for Service Pack 1 in video):
If you know you need to install Service Pack 4, download it here (warning this may take 15-20 minutes).
Check for ArcGIS ArcInfo & Extensions
This video shows how you check for these:
If you do not have ArcInfo and 3D Analyst and Spatial Analyst extensions, we will provide you with a fully functioning Education Edition, valid for one year. We will have to UNINSTALL your current version of ArcGIS, and then install the Education Edition (note that the ArcGIS Administrator can be used to switch this license from the Education Edition over to whatever license you or your company may have without uninstalling the software). Note that these installations require administrator privileges on the computer.
Make sure your extensions are turned on
See here for how to check if you extensions are enabled, or watch this video: