android - shadowed screen after android settings view

Question

I've got an issue with the android app im developping. When i open the settings menu, if i press the return button once, the main activity show up but it's shadowed (see the screenshot). Then i have to press the return button once again to unfreeze the main view and menu...

Screenshot

AndrdoidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="lauzon.eric.dataloger"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="7" />

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

<application android:icon="@drawable/ic_launcher" android:label="@string/app_name"  android:theme="@style/AppTheme">
    <activity android:name=".MainActivity" android:label="@string/title_activity_main" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity> 

    <activity
        android:name=".BrowseActivity"
        android:label="@string/title_activity_browse" 
    /> 

    <activity android:name="SettingsActivity" />


</application>

How i start the settings view

startActivity(new Intent(this, SettingsActivity.class));

SettingsActivity.java

import android.os.Bundle;
import android.preference.PreferenceActivity;

public class SettingsActivity extends PreferenceActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.settings);

}

@Override
    public void onBackPressed() {
        finish();
        return;
    }
}