I recently upgraded from 10.0 to 10.3 and am having a LOT of crashes when trying to launch the app. I have been using MXD's started in 10.0 but re-saved under 10.3 as well as ones started fresh in 10.3, both seem to experience crashes on launch. I have also tried just launching the app with no document to start a blank MXD and also get crashes on launch. Each time it is at the very end stages of the launching process, application windows have spawned, things seem fine, then right at the end it crashes.
I did find an old python 2.6 folder on my C: drive from 10.0 which I removed to see if that would help as I know 10.3 uses python 2.7, but no change.
It's getting very frustrating as launching the program has become tedious, with it crashing repeatedly, then mysteriously launching just fine, working for a bit, then I try and open another instance and I get crahses on the new instance, or I close the working instance down and try to restart the exact same MXD and I get non-stop crashing.
I am running Windows 7, have updated to the latest updates.