Element 'system.webServer' has invalid child element 'rewrite'. Should I fix this, and how?

The updated schema here fixed this for me.

http://ruslany.net/2009/08/visual-studio-xml-intellisense-for-url-rewrite-1-1/

Make sure you change the script for VS2010:

ruslany responded on 20 Oct 2009 at 7:10 pm #

@Gene: This is be because the XML schema cache is located in a different location in VS2010. Can you open the UpdateSchemaCache.js and replace this line:

var vs9CommonTools = shell.ExpandEnvironmentStrings( “%VS90COMNTOOLS%” );

with this line:

var vs9CommonTools = shell.ExpandEnvironmentStrings( “%VS100COMNTOOLS%” );

After that try running the script and see if that helps.