I upgraded to IntelliJ Idea from 12.0.4 to 12.10 and from now on, all the modules in my Android project give the ERROR:
Error: Default Activity Not Found
I reverted back to 12.0.4 and everything works alright again.
Could I get any ideas as I think it might be an issue with a missing plugin. Since the plugin is not installed, it is not able to find the default activity. Another thing could have been a local config, but I doubt it. I deleted the configuration folder to verify and that didn't change anything.