I had the same problem, mostly because I read the instructions on the install script literally. When it said to make the uploads, templates_c, and cache directories readable by all, I did so by chmodding them to 766. The
install script then gave me the green light to proceed.

However, what really was needed was a chmod to 777 on those
directories. After I did that, everything worked fine.

Really, the install script should check for 777 permissions, and not simply that those three directories are writeable.

My mistake, but fortunately it only took me about half an hour to figure out.