Are you on Windows, or Mac OS?
The first two things that I would consider, would be your video and your audio driver. That freezing at "white screen" might indicate an issue with the video driver, but it never hurts to update the audio driver too, as it can hang a program.
What make/model video card?
What is the currently installed number/date of your video driver?
Thanks, I have BETA Geforce drivers (295), will try to revert to 285.
OS is Win 7 x64
Thank you for that info, and so very quick too.
Fingers x'ed that the video and audio drivers will fix things. If not, I am sure that others will have a few more questions, and likely more suggestions.
Had shift held to refresh PluginCache.
Seems to have fixed startup so far.
Edit (2012-02-14): Found a reliable cause of issue. Following scenario makes a difference in having the startup hang or not (reboot to fix): quit a software like Skype
-- unless it was quit while a project is running, next startup of premiere would crash anytime (i.e. quitting software at welcome screen of premiere will make next startup crash). As long as software is kept open or never opened, startup appears safe everytime. I wonder if that scenario renders that issue on other config as well. Unless there remains unresolved mess with untested apps that would require disk format to fix, I would have to determine what is being specific to my problem.
ASUS SABERTOOTH X79
G.SKILL RIPJAWSZ F3-14900CL9Q2-32GBZL
INTEL i7-3930K + NVIDIA EVGA GEFORCE GTX570
CRUCIAL M4 128GB
Beta NVIDIA drivers work fine.
Edit (2012-02-17): 1866MHz RAM from G.Skill downclocked to 1600MHz. Persists. Explorer.exe must be ended and re-run to fix hang.