Solved! Go to Solution.
Talk about a FAQ -- I should probably sticky this, as keeping a clean app profile can resolve a lot of Desktop issues.
[thread=90076]Resetting your ArcGIS application profile[/thread]
Resetting your ArcGIS application profile <- added link, 10/10/2014
Help! I am having a similar problem trying to install the education version of ArcGIS 10. I have unistalled, reinstalled, updated .net, unistalled, reinstalled, deauthorized and authorized, rebooted....
Some random thoughts...
Have you deleted your user profile (rename %APPDATA%\ESRI to ESRI-old)?