I have been having trouble with doing anything in C5, from simply uploading an image, to updating the system with any file permissions other than 777. I was recently hacked and reset all my file permissions to 755 thinking that with ownership still writeable I should be secure while still being able to maintain my site. But I can't do anything. For example, when I try to upload an image I get this error message:

Unable to copy file to storage directory. Please check permissions on your upload directory and ensure they can be written to by your web server.

It takes forever to change the whole site back and forth from 777 to anything else and back again. I just can't do it any time I need to update. Any ideas what could be going on?

Thanks everyone.