Jelle Druyts

Another source of getting the wrong version of your code (see my post on Various Caches) can be because your references (real ones, not Project References) in Visual Studio are wrong, so make sure they point to the correct location of the dll. Even if you have set them right before, Visual Studio can still make them go wrong sometimes. And even then, I have noticed that the compiler may use another location than the one you are referencing. Needless to say this can be very frustrating and I haven't found a solution for this yet, sadly. The biggest problem with references is the "copy local" flag (in the reference's properties), which makes a copy of the referenced dll in the bin folder of your project. This makes it easy to run your project because you don't need to register your dll's in the GAC or place them in your DEVPATH. Of course, the drawback is that if they aren’t correctly updated to match the current version (that is, if your reference is wrong), you will be working with an older copy.

If it's in any way possible - and logical within your project - use Project References. I've never seen them go bad.