I had a very interesting case last week. Whenever we tried to open an Orchestration in Visual Studio 2008 we get the following error:

Package 'ODPackage' has failed to load properly (GUID = {2F926337-2BFB-46AB-BBC4-A955CE25FF6F}).)

 What was interesting is that we were able to open some orchestrations in certain projects. Also the projects that were throwing the error, if we added them to a new solution then the files would open but as soon as we saved the solution and tried to open the orchestration file, we would get the error again.

While debugging the solution, we found that the problem was related to certain project files that did not have an file extension. In VS 2008, when the project is opened we check for file types by looking at file extensions. If the file extension is not present then we error out.

The easy workaround to this is to add an file extension to the files that are missing them or exclude them for the project.

Customer also mentioned that folders with no files in them may also cause this problem.