Also check that the directory your files are being saved to before being moved is accessible under the open_basedir setting.
I had this issue where the open_basedir was set only to my hosting directory by my host provider, and the /tmp directory where the files are uploaded to initially needed to be accessible.
You can test this by writing or finding online a quick PHP upload script, turn on display_errors and check the error returned when you try uploading an image or file.
