Could well be the NVidia Graphics card here.
I have seen the exact same problems - and much, much worse - with 4.01 on a GE Force GO7300 chip.
4.01 will not even launch stably.
Yes, the EN7600GS card is not on the recommended list of Premiere.But, the initial crash when opening Premiere with the exe file is always solved by opening an existing project and after that opening a new project in Premiere.
Now my Media encoder problem is solved : I fortunately made a Norton Ghost backup of disc C after installing Premiere CS4 and the Media encoder update (not the premiere 4.01 update). I restored my disc C to that point and everything works fine.No problems with the media encoder neither with transitions of stills.
Lesson 1: never update a system that works
Lesson 2 : Backups are better than Raid, raid only stores your errors.
I was having all sorts of crashing errors on importer process. It had to do with dvacore.dll After exhausting all options I didn't update to 4.01 and that has fixed the error. The computer that was having the problem was XP 64. Seems to work fine on Windows 7 RC. Hopefully this helps someone that lands on this post.