Unfortunately, Archos has removed the present firmware from its servers, thus making the download impossible. However, you can still get a newer software version for the same device: download ARCHOS 605 WiFi (20GB-160GB) Tablet Firmware 2.1.04.
It is highly recommended to always use the most recent driver version available.
Try to set a system restore point before installing a device driver. This will help if you installed an incorrect or mismatched driver. Problems can arise when your hardware device is too old or not supported any longer.