System.xml not referenced error

Jun 1, 2011 at 6:06 PM

I have no idea why I'm getting this error since the T4toolbox.tt has the reference.  But when i try and generate I get an error on line 420 of LinqToSqlGenerator.tt

 

Has anyone seen this? I don't know how to get past it.  I have a clean install of T4 toolbox with no custom changes at all.  Running under VS2008.