ResolutionMake sure that /tmp directory has the right permissions:
ls -lad /tmp
drwxrwxrwt 32 root root 69632 Dec 6 10:06 /tmp
If the /tmp directory is a symlink to some other place you have to change "upload_tmp_dir" option in /etc/php.ini to a real temporary directory path and restart Apache.
Also, make sure that there is enough free disk space in /tmp.