Erro ao abrir câmera

Quando a aplicação tenta abrir a câmera, o locgat mostra a mensagem: "Unable to create external files directory"

Esse é o meu Android.manifest, com a permissão para escrever em arquivos externos

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="br.com.caelum.cadastro"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <uses-permission android:name="android.permission.CALL_PHONE"/>
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.READ_SMS" />
    <uses-permission android:name="android.permission.SEND_SMS" />
    <uses-permission android:name="android.permission.WRITE_SMS" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.CAMERA" />



    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >

        <activity android:name=".ListaAlunosActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>

        <activity android:name="br.com.caelum.cadastro.FormularioActivity"
                  android:label="@string/app_name" />



    </application>

</manifest>

Alguem tem uma ideia do que poderia estar causando o problema?