problem with eclipse

i saw that android 2,3 is ready so i tried to install it in my eclipse.Firstly,i went to "Android SDK and AVD mana开发者_开发知识库ger" in my installed packages and i updated them all.Secondly, i went from help to check for updates,i was waiting eclipse to download them and finally i restarted my eclipse!my problem is that all my old apps are not playing now and they have a red x in the package explorer.i wrote a helloWorld app in 2,3 android and its playing but as i try to run my old apps ,eclipse says that i have error in my code.please help,i m confused!!:)

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Do you still have your R.java in the gen/ folder ?

I got similar issue with new compiler in SDK 2.3, R.java sometimes disapears !

I manage to fix this by restarting eclipse and/or performing a clean in the projects.