If uploading with Director fails, it usually is either an issue with your .htaccess file or with the upload_tmp_dir setting in PHP.

.htaccess

Make sure the ssp_director/.htaccess file has been uploaded to your install. You may need to turn on hidden files in your FTP client to see the .htaccess file.

If the file is in place and uploads still fail, find this portion of the .htaccess file:

# <IfModule mod_security.c>
# 	SecFilterEngine Off
# 	SecFilterScanPOST Off
# </IfModule>

<IfModule mod_security.c>  
  SetEnvIfNoCase Content-Type "^multipart/form-data;" "MODSEC_NOPOSTBUFFERING=Do not buffer file uploads"  
</IfModule>

Change that to read this instead:

<IfModule mod_security.c>
    SecFilterEngine Off
    SecFilterScanPOST Off
</IfModule>

upload_tmp_dir

If the upload appears to complete but then redirects to an empty content page, then there is probably an issue with the upload_tmp_dir setting in PHP. Check with your host to ensure that the upload_tmp_dir setting is correct, is writable by the webserver and is not full.