Incorrect values when I select a radioButton in ListPreference

I have a Preference activity which uses a List Preferences as defined by my XML file:

<?xml version="1.0" encoding="utf-8"?>
    <PreferenceScreen
            xmlns:android="http://schemas.android.com/apk/res/android">
        <PreferenceCategory
                android:title="sync">
            <ListPreference
                    android:key="key_sync_period"
                    android:title="Sync"
                    android:summary="%s"
                    android:dialogTitle="Sync frequency"
                    android:entries="@array/sync_period_entries"
                    android:entryValues="@array/sync_period_values"
                    android:defaultValue="1800" />
        </PreferenceCategory>
    </PreferenceScreen>

arrays.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="sync_period_entries">
        <item>15 min</item>
        <item>30 min</item>
        <item>45 min</item>
        <item>1 hour</item>
    </string-array>

    <string-array name="sync_period_values">
        <item>900</item>
        <item>1800</item>
        <item>2700</item>
        <item>3600</item>
    </string-array>
</resources>

When I start my app, change this setting, I see the following:

• the app writes to a defaultSharedPreference file value = 1800
• I change it to "15 min" and see value = 900 - ok, all right
• I change it to "45 min" and see value = 60 - ???
• I change it to "1 hour" and see value = 180 - ???????
• I change again it to "30 min" and see value = 1800
• I change it to "1 hour" and see value = 180 - why?

Why do I see these values (60, 180)? Where did they come from?

Update 1:

if (key.equals("key_sync_period"))
{
    ListPreference syncPref = (ListPreference) findPreference(key);
    syncPref.setSummary(syncPref.getEntry());
    long seconds = Long.valueOf(sharedPreferences.getString(key, "1800"));
}

The system writes defaultSharedPreferences. I see preference file from ddms and see that the system written wrong value.

The problem was in the Idea 12CE, I deleted the project and imported it again... and problem was solved.