This happened to me when I tried 4.0 as well. What I did to fix it was after a fresh install, I installed the restricted drivers it said it had for me. After that was installed I opened up envy and then installed the latest ati driver ( I might have had to do it manually, I dont quite remember) but then it worked fine. It seemed to configure everything correctly after that no more white screen. I however went back to celena and find beryl to be faster. In Daryna, I could never get tomboy notes to load, and the mint menu would take a full minute to load after hitting the "daryna" button.
Enjoying the Mint Experience
"(to touch the earth is to have harmony with nature)" -hippy