title: ClickOnce fails with invalid manifest error via programmatic update but not framework update
body: <p>We have been distributing a WPF application via ClickOnce for a couple of years. I am locally testing a forthcoming update which will upgrade it from .NET 3.5 to .NET 4.0 (users have been warned in advance to upgrade their .NET version if they have not already).</p>
  
  <p>We do the ClickOnce updates programmatically via a "Check for updates" menu item. I am finding that for this particular update, it downloads the update successfully through the API but when it tries to install I get this error relating to an Infragistics DLL:</p>
  
  <p>"Exception occurred loading manifest from file InfragisticsWPF4.DataPresenter.v11.1.dll: the manifest may not be valid or the file could not be opened."</p>
  
  <p>This causes the app to close there. When I then try to relaunch it from the shortcut, I get the ClickOnce framework's own "Update available" dialog because the app is still not up to date - and when I let it update, it successfully re-downloads, installs, and starts up fine. I have tested this whole process several times and it's consistent.</p>
  
  <p>I don't know whether this has anything to do with Infragistics specifically, but as part of the update several Infragistics DLLs are being upgraded from WPF3 to WPF4. </p>