I get a blank page after step 4. I am installing on a windows box with vBulletin integration. I've double checked the settings on step 4 and all looks good.
I've also noticed that I get a blank page when going to the forums.
I would think your having an issue with your forum then. Since your installing with forum integration and you go to the last step you also have an issue with your photopost.
That wasn't writeable, but i've changed that and it still stops in the same place. I went back, dropped the pp_ tables and started the install from the beginning but still no luck.