Thanks to Mark for this one:
Driver Verifier is a tool for monitoring Windows kernel-mode drivers and graphics drivers. Microsoft strongly encourages hardware manufacturers to test their drivers with Driver Verifier to ensure that drivers are not making illegal function calls or causing system corruption. Driver Verifier has been enhanced with new tests and features for Beta 2 of the next release of the Microsoft® Windows® family of operating systems, code-named Windows "Whistler."

Read more