I have had this happen to me four times so far, at least once before 9.0.1.
The Designer hangs while doing something. It may be related to some recent creation of templates, although once it was due to cancelling a deployment. At that point there is nothing you can do. Restarting the Designer does not work. It hangs at the splash screen.
I have tried a complete disk clean, including all the places (and there are many) the designer stores files. I have made a complete sweep of the reigistry as well, a complete uninstall and reinstall. The Designer will still never start.
This has happened on XP Pro SP2 and Windows 7 Pro 64, so it is not the OS.
Where can I look to find the cause?