Asynchronous image provider crashes application sometimes

My qml view is ListView and delegate is Image showing images loaded from Internet. I wanted to cache loaded images on disk. I implemented my own QDeclarativeImageProvider which uses its own QNetworkAccessManager to load image from Internet and save it to disk. QML Image element has asynchronous flag set to true and my QDeclarativeImageProvider is Image type loader (not Pixmap).

It seems that quite often this causes application to crash. Debugging shows that it crashes always to line 1133 in qcoreapplication.cpp

QtCored4.dll!QCoreApplication::postEvent(QObject * receiver=0x039e97a0, QEvent * event=0x0394f670, int priority=0) Line 1133 + 0x3 bytes
QtCored4.dll!QCoreApplication::postEvent(QObject * receiver=0x039e97a0, QEvent * event=0x0394f670) Line 1094 + 0xf bytes
QtDeclaratived4.dll!QDeclarativePixmapReply::postReply(QDeclarativePixmapReply::ReadError error=NoError, const QString & errorString=

{...}, const QSize & implicitSize={...}

, const QImage & image=

{...}) Line 256 + 0x59 bytes
QtDeclaratived4.dll!QDeclarativePixmapReader::processJob(QDeclarativePixmapReply * runningJob=0x039e97a0, const QUrl & url={...}

, const QSize & requestSize=

{...}

) Line 465
QtDeclaratived4.dll!QDeclarativePixmapReader::processJobs() Line 441
QtDeclaratived4.dll!QDeclarativePixmapReaderThreadObject::event(QEvent * e=0x039e9968) Line 398

Is there a better way to implement caching images to disk?