Error after changing OS

[szabi42]

I have a problem with my project, my XML file is any error but logcat find one...\[code\]05-30 19:05:05.348: E/AndroidRuntime(628):at com.Dolce.Main.onCreate(Main.java:23)\[/code\]And my line 23: \[code\]setContentView(R.layout.accueil);\[/code\]My project worked before my changing OS.I have already tried cleaning the project and erasing R.java for regeneration.