Opening the Resolve Conflicts window programaticly

Hi,

I am trying to open the Resolve Conflicts window when a tfs get operation gives me a conflict. This is the code I am using. 

foreach (Conflict c in conflicts)
   {
   if (Workspace.MergeContent(c, false))
      {
      c.Resolution = Resolution.AcceptMerge;
      Workspace.ResolveConflict(c);
      }
   }

But the MergeContent throw an encoding error :

Microsoft.TeamFoundation.VersionControl.Client.InvalidFileTypeException
The file encoding -2 is not a valid encoding
I am using TFS 2012 with visual studio 2013 and the encoding of all my files is Windows-1252.
Can somebody help me with this error ? or is there a better way to open the Resolve Conflicts window from inside C# code ?