title: Cannot step into .NET framework source with VS2008 SP1
body: <p>Somehow my VS2008 SP1 has lost the ability to step into .NET framework sources. I've played around with checkboxes to no end; I've re-deleted the Symbol cache folder a dozen times; and I've tried all kinds of debug symbol servers.</p>
  
  <p>All it does is download some .PDB files, but when I try to select a stack frame in .NET, I always get the message about no source available and "do you want to view disassembly".</p>
  
  <p>What gives?</p>
  
  <p><strong>Added:</strong> Web application; Windows Vista Business x32; .NET 3.5 SP1.</p>