It looks very much like a .NET bug! A recent update to the .NET framework screwed up the handling of DateTimePicker controls in older, previously normally functioning assemblies, and the appearance of affected controls can be similar to what you show. The really infuriating thing (for those of us who program in .NET languages) is that simply rebuilding the Application from the source code in the updated environment doesn't fix the problem - you have to recreate a working facsimile of the affected form from scratch, replace the old form with the newly created one, and rebuild the Application. There are some other, more complicated, workarounds reported, but I know of absolutely no way of fixing it without access to the source code and the Visual Studio programming environment. It will have to be fixed by the people who developed the module.