Theme downloading problems

Hi I’m trying to download a theme and the first time I encountered a server error, I tried again and now every time it says this:

Downloading install package from http://wordpress.org/extend/themes/download/suffusion.3.3.6.zip.
Unpacking the package.
Installing the theme.
Destination folder already exists. D:\Hosting\5712008\html\wordpress/wp-content/themes/suffusion/
Theme Install Failed.

Sounds to me like it thinks I already installed it, but it doesn’t show up in my available themes. Any thoughts?