I've been using C4D for a couple years now and I've never experienced this problem. I don't know what I inadvertently clicked on to change something, but whenever I try to render a still image I get this error message...
"files cannot be written - please check output paths"
It looks like its trying to render a full movie, but that's not what I want to do.
You were right Greg. I had a similiar problem and in my case all I had to do was to go to the save tab in render settings. I found the path I wanted to save my file to and it seems as if the problem was that C4D would automatically populate the project name as the destination folder. See example :
/Volumes/G-DRIVE/Jae Mac "She Wanna" Video/After Effects/C4D/project file
all i had to do was erase that "project file" and it rendered fine!
File...../Volumes/G-DRIVE/Jae Mac "She Wanna" Video/After Effects/C4D
Obviously it has to render to a folder not a file... duh..