Today I upgraded to Android SDK 2.3 and I also upgraded the Eclipse Plugin Androi Developer Tools 8.0 (from 0.9.9). I also upgraded my Java Development Kit to 1.6_22.
No
The way that helped me.
Take the following file from the working project: workspace/.metadata/.plugins/org.eclipse.core.resources/.projects/Working-project-name/.indexes
workspace/.metadata/.plugins/org.eclipse.core.resources/.projects/Working-project-name/.indexes
Replace the broken project file: workspace/.metadata/.plugins/org.eclipse.core.resources/.projects/Broken-project-name/.indexes
workspace/.metadata/.plugins/org.eclipse.core.resources/.projects/Broken-project-name/.indexes