I use VS 2012 RC with SL5 for Infrigistics 12.1, it is fine. Then I upgrade VS2012 RC to official version. and open the solution. Now I have problem:

Designer not working any more, got lot of invalid xaml markup. For example, even for I got error like:

XamlParseException:  [Line: 0 Position: 0]

at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.FrameworkElement_MeasureOverride(FrameworkElement element, Size availableSize)
   at System.Windows.FrameworkElement.MeasureOverride(Size availableSize)
   at System.Windows.FrameworkElement.MeasureOverride(IntPtr nativeTarget, Single inWidth, Single inHeight, Single& outWidth, Single& outHeight)

InnerException: None

Not sure why. How to resolve it?