I am getting the following error when referencing the assembly Microsoft.Office.Interop.Word in my asp.net application. The type 'Microsoft.Office.Interop.Word.ApplicationClass' exists in both 'C:\WINDOWS\assembly\GAC\Microsoft.Office.Interop.Word\11.0.0.0_71e9bce111e9429c\Microsoft.Office.Interop.Word.dll' and 'C:\WINDOWS\assembly\GAC\Microsoft.Office.Interop.Word\12.0.0.0_71e9bce111e9429c\Microsoft.Office.Interop.Word.dll' Previously, I was getting the error but the 12.0.0.0 was in the PIA directory under Visual Studio, but the error message was the same, except pointing to a different path. Since then, I copied the dll to the GAC, but with the same error. I thought that .Net was supposed to take care of this. Can anyone give me some help? Thanks BTW, I am doing this using Visual Studio .Net 2008