I have a rather big Android App project that is referencing several library projects. Everything was fine until i upgraded the eclipse ADT plugin to the newest version (v22)
Quoting Streets of Boston from his adt-dev post:
When upgrading, the 'Order and Export' of the new 'Android Private Libraries' is not always checked. And the android-support-v4.jar is now in this 'Android Private Libraries' section.
To fix this, go to 'Order and Export' and check 'Android Private Libraries'. Then refresh/clean/rebuild.
After you done this 'fix' for a library project, you may need to just close and re-open any depending project, because they may not see this 'fix' immediately.
Give this a shot and with luck it will solve your problem.