Before your reset all of your settings, try this...
I had a similar issue and traced it to missing DLLs in the obj\Refactor folders. I wrote this VB script (which I saved as reff.vbs in one of the folders from my path environment variable) and run it from a command prompt. When "Find All References" or "Refactor > Extract Method" fails, rebuild your solution, then run this:
'' reff.vbs ''
Dim refFile, wsh, objFSO
Set wsh = CreateObject("wscript.shell")
Set objFSO = CreateObject("Scripting.FileSystemObject")
RefactorFolders "c:\Source" '' Put your root source folder here
Set objOutputFile = objFSO.OpenTextFile("RefreshRefactor.bat", 8, True)
objOutputFile.WriteLine(refFile & "")
objOutputFile.Close
wsh.Run "RefreshRefactor.bat", 1, True
Set wsh = Nothing
Set objFSO = Nothing
Sub RefactorFolders(strFolder)
Set objFolder = objFSO.GetFolder(strFolder)
For Each SubFolder in objFolder.SubFolders
If Right(" " & SubFolder.Path, 9) = "\Refactor" Then
Set objBinFolder = objFSO.GetFolder(Left(SubFolder.Path _
, Len(SubFolder.Path) - 8))
Set files = objBinFolder.Files
For Each binFile In files
chk = Right(" " & binFile.Path, 4)
On Error Resume Next
If chk = ".exe" Or chk = ".dll" Or chk = ".pdb" Then
refFile = refFile & "copy /y """
refFile = refFile & binFile.Path & """ """
refFile = refFile & SubFolder.Path & "\"" "
refFile = refFile & vbCrLf
End If
On Error Goto 0
Next
End If
RefactorFolders SubFolder.Path
Next
Set objFolder = Nothing
End Sub