Why am I getting this error? Apparently, most people have this working on like.. the first try.
Never mind. I asked in the silverstripe forum and got an answer.
you have to install the latest version (version 2.1 rc1 at the moment) and create silverstripe-cache on that directory (the one with folders cms, sapphire, etc
I also had problems that were resolved by two steps...create a folder called silverstripe-cache with write permissions and choosing thee blank install (not preloaded with demo info)
hope that helps others.