Possible reasons:
* The download takes to long to be saved.
* For this download, in the background your Internet Service Provider has assigned a new IP address. If you are for example an AOL customer, or use a similar Service Provider, please try to use a different browser.
If this problem persists to exist, you may want to purchase a Premium Account. As Premium users are not checked against their IP address, this problem will not occur. Or your internet connection is too slow to download the complete file within the session time.
