My question to you - did you auto move your files from an old comptuer to the new one?
I had the white screen, and could only boot on safe mode to log in. (hold SHIFT after the chime, release it when you see a progress bar).
My issue - some very old items in the startup items folder; which apparently weren't compatible with SL. (through checking I also removed corrupt fonts, and old System Preference items)
I would boot up safe (or with CD), then check out <hard drive>/Library/Startup Items and see if there are old items in there. Either remove them (and store in a folder just in case), or update the software. mac boots fine now.
