Trash your preferences. Hold down the Alt key when you launch Pr, and keep holding it until the Welcome/Project screen appears.
I have the same problem. Tried the Alt idea. No luck. On the splash screen it just stops with the message "Loading ExporterQuickTimeHost.prm". This happens every time. I guess I need to reinstall Premiere Pro unless there is another solution. Please advise.
I've had this happen now and then. A reboot usually does it, or you can go into the task manager and turn off anything quicktime related and any adobe apps, then restart premiere.