I accidentally entered S# for and aspx page language instead of C#. So the page directive looks like <%@ Page Language="S#" .... %> Build337, VS2005 JetBrains.ReSharper.Util.InternalErrorException: Failed to load language service for language PsiLanguageType:UNSUPPORTED_LANGUAGE An exception has occurred ---> JetBrains.ReSharper.Util.InternalErrorException: Failed to load language service for language PsiLanguageType:UNSUPPORTED_LANGUAGE at JetBrains.ReSharper.Util.InternalErrorException..ctor(String, Exception) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\InternalErrorException.cs:line 28 column 7 at JetBrains.ReSharper.Util.Logger.Fail(String, Object[]) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 144 column 9 at JetBrains.ReSharper.Util.Logger.Assert(Boolean, String, Object[]) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 137 column 5 at JetBrains.ReSharper.Asp.LanguageService.MyFactory.CreateLexer(Char[]) in c:\Agent\work\Server\ReSharper2.5\src\Asp\src\LanguageService\AspLanguageService.cs:line 32 column 9 at JetBrains.ReSharper.Psi.Parsing.TokenBuffer..ctor(ILexerFactory, Char[], Int32, Int32, CheckForInterrupt) in c:\Agent\work\Server\ReSharper2.5\src\Psi\src\parsing\TokenBuffer.cs:line 35 column 7 at JetBrains.ReSharper.CodeInsight.CachingLexerServiceImpl.GetCachingLexer(ITextControl, ProjectFileType) in c:\Agent\work\Server\ReSharper2.5\src\IDECore\src\CachingLexerServiceImpl.cs:line 104 column 9 at JetBrains.ReSharper.CodeInsight.CachingLexerServiceImpl.GetCachingLexer(ITextControl) in c:\Agent\work\Server\ReSharper2.5\src\IDECore\src\CachingLexerServiceImpl.cs:line 134 column 7 at JetBrains.ReSharper.CodeInsight.CodeCompletion.SessionStarter.OnBeforeCommandFinished() in c:\Agent\work\Server\ReSharper2.5\src\CodeInsight\src\codeCompletion\CodeCompletionController.cs:line 145 column 17 at JetBrains.ReSharper.Shell.BeforeCommandFinishedHandler.Invoke() at JetBrains.ReSharper.Shell.VSIntegration.VSCommandProcessor.EndCommand() in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\Shell\VSCommandProcessor.cs:line 192 column 13 at JetBrains.ReSharper.Shell.CommandCookie.Dispose() in c:\Agent\work\Server\ReSharper2.5\src\Shell\src\CommandProcessor.cs:line 41 column 5 at JetBrains.ReSharper.TextControl.Impl.TextControlManagerImplBase.Type(ITextControl, Char) in c:\Agent\work\Server\ReSharper2.5\src\TextControl\src\impl\TextControlManagerImplBase.cs:line 165 column 51 at JetBrains.VSAddin.TextControl.VSTextControlManager.DoType(VSTextControl, Char) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\VSTextControlManager.cs:line 94 column 7 at JetBrains.VSAddin.TextControl.MyCommandFilter.TryDelegateToReSharper(UInt32, IntPtr, UInt32, IntPtr, Guid&) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\VSTextControl.cs:line 656 column 15 at JetBrains.VSAddin.TextControl.MyCommandFilter.Exec(Guid&, UInt32, UInt32, IntPtr, IntPtr) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\VSTextControl.cs:line 611 column 13 at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr, IntPtr, Int32, IntPtr, IntPtr) at System.Windows.Forms.NativeWindow.DefWndProc(Message&) at System.Windows.Forms.NativeWindow.WndProc(Message&) at JetBrains.VSAddin.TextControl.VsEditorParentWindow.WndProc(Message&) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\Windows\VsEditorParentWindow.cs:line 225 column 11 at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr, Int32, IntPtr, IntPtr) at JetBrains.ReSharper.Util.Logger.Fail(String messageFormat, Object[] args) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 144 — End of inner exception stack trace — at JetBrains.ReSharper.Util.Logger.LogExceptionEx(Exception, String, Boolean) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 350 column 9 at JetBrains.ReSharper.Util.Logger.LogException(Exception) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 362 column 5 at JetBrains.ReSharper.Util.Logger.Fail(String, Object[]) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 148 column 9 at JetBrains.ReSharper.Util.Logger.Assert(Boolean, String, Object[]) in c:\Agent\work\Server\ReSharper2.5\src\Util\src\Logger.cs:line 137 column 5 at JetBrains.ReSharper.Asp.LanguageService.MyFactory.CreateLexer(Char[]) in c:\Agent\work\Server\ReSharper2.5\src\Asp\src\LanguageService\AspLanguageService.cs:line 32 column 9 at JetBrains.ReSharper.Psi.Parsing.TokenBuffer..ctor(ILexerFactory, Char[], Int32, Int32, CheckForInterrupt) in c:\Agent\work\Server\ReSharper2.5\src\Psi\src\parsing\TokenBuffer.cs:line 35 column 7 at JetBrains.ReSharper.CodeInsight.CachingLexerServiceImpl.GetCachingLexer(ITextControl, ProjectFileType) in c:\Agent\work\Server\ReSharper2.5\src\IDECore\src\CachingLexerServiceImpl.cs:line 104 column 9 at JetBrains.ReSharper.CodeInsight.CachingLexerServiceImpl.GetCachingLexer(ITextControl) in c:\Agent\work\Server\ReSharper2.5\src\IDECore\src\CachingLexerServiceImpl.cs:line 134 column 7 at JetBrains.ReSharper.CodeInsight.CodeCompletion.SessionStarter.OnBeforeCommandFinished() in c:\Agent\work\Server\ReSharper2.5\src\CodeInsight\src\codeCompletion\CodeCompletionController.cs:line 145 column 17 at JetBrains.ReSharper.Shell.BeforeCommandFinishedHandler.Invoke() at JetBrains.ReSharper.Shell.VSIntegration.VSCommandProcessor.EndCommand() in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\Shell\VSCommandProcessor.cs:line 192 column 13 at JetBrains.ReSharper.Shell.CommandCookie.Dispose() in c:\Agent\work\Server\ReSharper2.5\src\Shell\src\CommandProcessor.cs:line 41 column 5 at JetBrains.ReSharper.TextControl.Impl.TextControlManagerImplBase.Type(ITextControl, Char) in c:\Agent\work\Server\ReSharper2.5\src\TextControl\src\impl\TextControlManagerImplBase.cs:line 165 column 51 at JetBrains.VSAddin.TextControl.VSTextControlManager.DoType(VSTextControl, Char) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\VSTextControlManager.cs:line 94 column 7 at JetBrains.VSAddin.TextControl.MyCommandFilter.TryDelegateToReSharper(UInt32, IntPtr, UInt32, IntPtr, Guid&) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\VSTextControl.cs:line 656 column 15 at JetBrains.VSAddin.TextControl.MyCommandFilter.Exec(Guid&, UInt32, UInt32, IntPtr, IntPtr) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\VSTextControl.cs:line 611 column 13 at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr, IntPtr, Int32, IntPtr, IntPtr) at System.Windows.Forms.NativeWindow.DefWndProc(Message&) at System.Windows.Forms.NativeWindow.WndProc(Message&) at JetBrains.VSAddin.TextControl.VsEditorParentWindow.WndProc(Message&) in c:\Agent\work\Server\ReSharper2.5\src\VSAddin\src\TextControl\Windows\VsEditorParentWindow.cs:line 225 column 11 at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr, Int32, IntPtr, IntPtr)