it's completely blank....i've had the screen looks like yours already when there's no files in a directory.
usually i can sort the problem by pressing the back button so it's not a fatal bug or anything.
what i've found so far with cool reader is it handles text files rather better than kindle. it seems to format large paragraphs better. mobi stuff gets corrupted a bit tho with missing pictures and links.
i haven't tried an epub book yet.