One possible solution:-
Summary: make sure you are using import com.yourpkgdomainname.yourpkgappname.R
instead of import android.R
Details: The problem occured when I changed ID of a label which was being referred in other places in the layout XML file. Due to this error, the R file stopped generating at first. Eclipse is bad in handling errors with the layout files.
When I corrected the ID reference (with project clean few times and Eclipse restarts, I noticed that my import packages now has:
import android.R
Changing it to following fixed the error:
import com.example.app.R