I spent a couple of hours trying to figure out why I keep getting an exception with an error code of 0x80040E14 whenever I try to programmatically update a list item. Found this blog entry which describes exactly what I experienced. A quick fix for this...

Follow these simple steps to encrypt sections of your configuration files 1. Create a custom machine-level RSA key container by running aspnet_regiis.exe C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pc “MyKeys” -exp ...