I have an Interop assembly lying in GAC; Windows Explorer clearly shows it listed in the C:\\WINDOWS\\assembly folder. Yet, when I try to add a reference to it in f
C:\\WINDOWS\\assembly
"C:\WINDOWS\assembly" is a special folder which in Windows Explorer will list the assemblies (and the assembly info) within the various sub-folders.
For your case, you might need to point it to the physical path which is "C:\Windows\assembly\GAC_MSIL.....dll" within VS.NET.