Reinventing the wheel when new management come in, i.e. don't check their ego at the door. The new management think they have to make their mark/impact/whatever in the products/processes by throwing out the old's. I've seen new VP/CTO came in, canceled a release pending product, and promised to rebuild the product quickly with his oversight. As with any rewrite, the project dragged on and on. The product ended up delayed for a year and half. The company bellied up shortly after.