fix harcoded extension in metadata file - http://community.sharpdevelop.net/forums/t/12700.aspx

src/Main/Base/Project/Src/Services/DecompilerService/DecompilerService.cs

@@ -311,7 +311,16 @@ namespace ICSharpCode.SharpDevelop
 		{
 			// temp file
 			string tempFolder = Path.GetTempPath();
-			string file = fileName + ".temp.cs";
+			string file = fileName + ".temp";
+			if (ProjectService.CurrentProject != null) {
+				string language = ProjectService.CurrentProject.Language.ToLower();
+				if (language == "c#" || language == "csharp")
+					file += ".cs";
+				else
+					if (language == "vb" || language == "vbnet")
+						file += ".vb";
+			}
+			
 			string filePath = Path.Combine(tempFolder, file);
 
 			if (File.Exists(filePath))