XNA, .NET: Solving The located assembly's manifest definition does not match the assembly reference

Yup, ran across this one, which to the popular believe as the errors which every .net programmer should face. The problem arise when i tried to compile a new assembly version, and then when i compile/build old project, the project complains about The located assembly's manifest definition does not match the assembly reference. Tried to delete the assemblies, removing the references but to no avail.
Finally, i tried to modify app.config and then changes this line (yours might be similar)

<bindingRedirect oldVersion="0.0.0.0-1.4.0.0" newVersion="1.2.0.0"/>

Now the program compiles successfully. Hope to help someone else ;)

Ciaoo!