[2005] Release Folder

Perhaps I am misunderstanding something, but I used to use my solution's "Release" folder as a means for fellow coworkers to try out my application, as opposed to running a full install. I set all references with the exception of the included framework references (system.xyz, etc) to "Copy Local". Now, that being said, I could have sworn I used to just be able to have my coworkers copy the contents of the "Release" folder to their local drive and run the exe. Now when they try to do it, the application will run, but will fail to operate as expected when interacting with some of the project's referenced assemblies (which I also created and are part of the solution). Exceptions are not thrown, but rather functions are not succeeding where expected. For example, I wrote my own serialization routines to handle opening and saving of my native format, now that always returns failure. Running the same exe from the same folder on MY local machine works fine (as expected). Thoughts? Am I just being a donkey here?