When you copy a large file between a VMWare guest and the host, you might get the following error in the guest:

On the host, you will see the following event:

It is very annoying and is not so easily solved. The reason why this happens is explained in the VMWare knowledge base. This web page also contains more info. In essence, it happens because of a security feature in Windows 2003. Windows 2003 thinks a denial of service attack is happening because the transfer rate is higher than possible. The solutions are discussed in the VMWare KB article.