1) Stop Visual Studio
2) Find JetBrains.ReSharper.TaskRunner.exe
3) Drop read-only flag on the file
4) Run
CorFlags.exe JetBrains.ReSharper.TaskRunner.exe /32BIT- /Force
The assembly have now broken signature and VS/R# complains about that. But now you could debug your 64bit unit tests. More info would be probably here