fileupload.saveas size restriction

I am trying to upload files to a server. It works fine for under 4mb, but for file larger than 4mb, I get a page cannot be displayed error in IE.

I have been told I can change the size limit as follows:

maxRequestLength="11000"

But I still get the error for a 5mb file.

How can I allow 5mb files?

Also, if the user does go over my set limit, how can I make it so they recieve a message that their file was too big and are sent back to the page to try again rather than recieving a 'page cannot be displayed' page?

The config file and code are below.< ...