Is this related to the book Beginning ASP.NET 4 in C# and VB
? If so, can you specify chapter and page numbers?
If not, you're better off posting in a more general ASP.NET forum, located here: http://p2p.wrox.com/asp-net-4-539/
That said, the info you provided is not enough to say something useful about the problem. A ZIP download is normally not using AJAX, so something else must be going on. Can you provide more details about the problem and post the relevant code?