When this happens, it is important to check that the file size of the downloaded file corresponds to the indicated size on the web site.
If the sizes do not match, then the downloaded file is not complete.
First, clear your internet browser's cache. In Internet Explorer, you use the menu Tools / Internet options, then "delete temporary files". Then retry the download.
If the file is still truncated, then the file can have been truncated by your internet service provider's proxy server, or there can be another reason for the truncation. If the file is truncated by your internet provider, the truncated file will sit in his proxy cache for maybe a couple of days, and as long as it does, any renewed attempt to download will result in the same truncated file. You can try another internet provider. Alternatively, drop me an e-mail, and I'll e-mail you a copy of the file.
best regards,
Finn