This comes from one of my co-workers:
In the Web.config file, override the value of maxRequestLength for the application. For example, the following entry in Web.config allows files that are less than or equal to 8 megabytes (MB) to be uploaded:
<httpRuntime maxRequestLength="8192" />
Real Example: <httpRuntime executionTimeout="3000" maxRequestLength="51000"/>
Comments: I increase the Timeout from 300 to 3000 to allow more time on the upload. The file size is set to max at 51 MB.
(**Be careful when making changes to the Registry, it's always safer to back up the Registry, or at least the hive you're changing, just in case something breaks.**)
Change the following registry key to reflect the maximum number of bytes in decimal:
Real Example: Make sure you set the Decimal value to the number of bytes. So 50 MB converts to 52428800 bytes, or I put 53000000.
Reset Internet Information Services (IIS). To do this, click Start, click Run, type iisreset, and then click OK.
Real Example: CMD --> IISRESET
Hope this comes in handy.