This is a little arcane, easy to duplicate, and easy to workaround.
I have several old project files (*.aps) created with AVRStudio 4.12 SP4. Uninstall 4.12 and install 4.13 beta. Use Windoze Exploder to double-click (open) the .aps file -- AVRStudio wakes up, gives me the starting desktop, then crashes.
Workaround: Start AVRStudio 4.13 directly and then open the project file; it opens correctly. Save the project file and exit AVRStudio. I can now double-click on the .aps file from Exploder and everything works fine.