Hello, I have a very strange issue in my WPF project. The main window contains several wpf controls and winforms RichTextbox(don't ask me why) within WindowsFormsHost element. Richtextbox contains text. In some cases Richtextbox is not properly rendered when loading window (the right part is white like somebody uses erase tool and clears a rectangle). This situation is not so common (~20 users / 30 000) and it probably depends on hw. It occurs on XP machines. I have tried to force sw rendering, but it didn't help. Application is built in .net 3.5 SP1. Any idea?