The problem with most Microsoft OSs has little to do with making their design "cleaner, leaner, more stable". Vista is actually a very stable OS (from what I have seen from coworkers using it). However, the problem that Vista has (as this case shows) is their legacy support. WMF came out a long time ago and Microsoft still has to support it. They made a mistake in the parser many years ago and now they have to pay for it.