By default, ASP.NET permits only files that are 4,096 Kb to be uploaded to the Web server. When you try to upload a larger file you will get a “page could not be displayed message” within your browser.
Resolution
Add the following element to the web.config file (in the system.web section) of your web application and change the maxRequestLength according to your needs;
<httpRuntime
executionTimeout=”90″
maxRequestLength=”4096″
useFullyQualifiedRedirectUrl=”false”
minFreeThreads=”8″
minLocalRequestFreeThreads=”4″
appRequestQueueLimit=”100″
/>
Additional information
http://support.microsoft.com/kb/323245