Just to save some of you time...
On my Galaxy S v.2.3.3 Shared Preferences are not stored in:/data/data/YOUR_PACKAGE_NAME/shared_prefs/YOUR_PREFS_NAME.xml
but are now located in: /dbdata/databases/YOUR_PACKAGE_NAME/shared_prefs/YOUR_PREFS_NAME.xml
I believe they changed this in 2.3