monodevelop fails to open script on first run

[Select_Casey]

Hi, i just started using unity today and ive found my first problem, although its probably just noobishness on my part.

im doing the space shooter tutorial, and ive got to the scripts part, now i created my script and a folder for it and any way i try to open it in monodevelop it gives me an error message:

System.TypeInitializationException: The type initializer for ‘Boo.Lang.Compiler.TypeSystem.Types’ threw an exception. —> System.TypeLoadException: Could not load type ‘System.Runtime.CompilerServices.ExtensionAttribute’ from assembly ‘mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’.
at Boo.Lang.Compiler.TypeSystem.Types…cctor()
— End of inner exception stack trace —
at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionTypeSystemProvider.ObjectTypeImpl…ctor(IReflectionTypeSystemProvider provider)
at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionTypeSystemProvider…ctor()
at UnityScript.UnityScriptCompilerParameters…ctor(Boolean loadDefaultReferences)
at UnityScript.UnityScriptCompilerParameters…ctor()
at UnityScript.UnityScriptCompiler…ctor()
at UnityScript.MonoDevelop.ProjectModel.UnityScriptParserModule.ParseUnityScript(String fileName, String content)
at UnityScript.MonoDevelop.ProjectModel.UnityScriptParser.Parse(Boolean storeAst, String fileName, TextReader reader, Project project)
at MonoDevelop.SourceEditor.SourceEditorView.RunFirstTimeFoldUpdate(String text) in c:\BuildAgent\work\d478831d940d36a4\monodevelop\main\src\addins\MonoDevelop.SourceEditor2\MonoDevelop.SourceEditor\SourceEditorView.cs:line 734
at MonoDevelop.SourceEditor.SourceEditorView.Load(String fileName, Encoding loadEncoding) in c:\BuildAgent\work\d478831d940d36a4\monodevelop\main\src\addins\MonoDevelop.SourceEditor2\MonoDevelop.SourceEditor\SourceEditorView.cs:line 819
at MonoDevelop.SourceEditor.SourceEditorView.Load(String fileName) in c:\BuildAgent\work\d478831d940d36a4\monodevelop\main\src\addins\MonoDevelop.SourceEditor2\MonoDevelop.SourceEditor\SourceEditorView.cs:line 729
at MonoDevelop.Ide.Gui.LoadFileWrapper.Invoke(String fileName) in c:\BuildAgent\work\d478831d940d36a4\monodevelop\main\src\core\MonoDevelop.Ide\MonoDevelop.Ide.Gui\Workbench.cs:line 1201

please help. thx

[Select_Casey]

Sorry, close this and ignore me. i created the file as .js instead of .cs. my own oversight. i’m such a pleb lol

bows