Android- java.lang.IllegalStateException: Cannot perform this operation because the connection pool has been closed

I was reading through stackoverflow about this question and I still haven't found a solution. Sometimes my application face this problem. this is my error log,

12-31 10:58:28.025: E/AndroidRuntime(16322): FATAL EXCEPTION: Timer-0
12-31 10:58:28.025: E/AndroidRuntime(16322): java.lang.IllegalStateException: Cannot perform this operation because the connection pool has been closed.
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteConnectionPool.throwIfClosedLocked(SQLiteConnectionPool.java:1031)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteConnectionPool.waitForConnection(SQLiteConnectionPool.java:746)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteConnectionPool.acquireConnection(SQLiteConnectionPool.java:400)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteSession.acquireConnection(SQLiteSession.java:905)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteSession.executeForCursorWindow(SQLiteSession.java:834)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:62)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:144)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.sqlite.SQLiteCursor.getCount(SQLiteCursor.java:133)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:197)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at android.database.AbstractCursor.moveToFirst(AbstractCursor.java:237)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at com.eyepax.horseapp.data.dbadapters.ContactGroupDbAdapter.getContactGroups(ContactGroupDbAdapter.java:138)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at com.eyepax.horseapp.data.DataManager.getGroups(DataManager.java:1548)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at com.eyepax.horseapp.sync.ContactSync.contactGroupSync(ContactSync.java:43)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at com.eyepax.horseapp.service.SynchingService.callSync(SynchingService.java:77)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at com.eyepax.horseapp.service.SynchingService.access$0(SynchingService.java:70)
12-31 10:58:28.025: E/AndroidRuntime(16322):    at com.eyepax.horseapp.service.SynchingService$1.run(SynchingService.java:57)

This is the method which crashed in ContacGroupDbAdapter class,

/**
 * Returns ContactGroup.
 * 
 * @return ArrayList<ContactGroup>
 */
public ArrayList<ContactGroup> getContactGroups() {

    this.open();
    Cursor cursor = database.rawQuery("SELECT * FROM " + TABLE_NAME, null);
    ArrayList<ContactGroup> list = null;

    if (cursor != null && cursor.moveToFirst()) {
        list = new ArrayList<ContactGroup>();

        do {
            try {
                ContactGroup contactGroup = new ContactGroup();
                contactGroup.setGroupId(cursor.getString(cursor.getColumnIndex(GROUP_ID)));
                contactGroup.setGroupName(cursor.getString(cursor.getColumnIndex(GROUP_NAME)));
                contactGroup.setIsDeleted(cursor.getInt(cursor.getColumnIndex(GROUP_IS_DELETED)));
                contactGroup.setUpdatedDate(cursor.getString(cursor.getColumnIndex(GROUP_UPDATE_DATE)));
                contactGroup.setIsSync(cursor.getInt(cursor.getColumnIndex(GROUP_IS_SYNC)));

                list.add(contactGroup);
            } catch (Exception e) {

            }
        } while (cursor.moveToNext());

    }

    if (cursor != null)
        cursor.close();
    return list;
}

And that it crashed in the line cursor.moveToFirst() with this error. please help me to resolve this issue.