Not the story I'll ready to my daughter tonight, but the tale of a rename gone bad. When you're creating a web part in SharePoint 2010, and you rename your items from VisualWebPart1 to MyCoolWebPart, perform a Search in the Entire Solution scope for any remaining remnants of VisualWebPart1. There were a few...fix them up and your web part will register safely just fine & you'll be able to add it to your web part page.