c# - Duplicate Type With Name ' ' -

c# - Duplicate Type With Name ' ' -

i think broken. problem not code related. if creating new wpf project , seek compile next error:

error 1 unknown build error, 'duplicate type name '' in assembly 'system, version=4.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089'.' wpfapplication1

this happens on every wpf application want build.

i tried repairing .net framework, re-install visual studio, cleared global assembly cache etc...

edit: c# projects ...

c# .net wpf