following error occurs
========================
Every CAPTCHA can only be used once. The current CAPTCHA has already been used. Please click back, refresh the page and try again.

the registration page consists of these errors
=================================================
Warning: unlink(/tmp/captchasnet-random-strings/__time_stamp__) [function.unlink]: Permission denied in /home/blaagers/public_html/wp-content/plugins/wordpress-link-directory/captcha.php on line 78

Warning: unlink(/tmp/captchasnet-random-strings/etcrs61xwn4ci8kfc6bn665pr96bfe6rvjezzcxc) [function.unlink]: Permission denied in /home/blaagers/public_html/wp-content/plugins/wordpress-link-directory/captcha.php on line 78

Warning: unlink(/tmp/captchasnet-random-strings/k1i895g49kpfmhqkfnp3xyvcl5izxtpzlwt9sxo5) [function.unlink]: Permission denied in /home/blaagers/public_html/wp-content/plugins/wordpress-link-directory/captcha.php on line 78

Warning: touch() [function.touch]: Utime failed: Permission denied in /home/blaagers/public_html/wp-content/plugins/wordpress-link-directory/captcha.php on line 84

Warning: fopen(/tmp/captchasnet-random-strings/4bkvp6nzxtl6v58qbwh77mvpdlwjfciy4clblr4e) [function.fopen]: failed to open stream: Permission denied in /home/blaagers/public_html/wp-content/plugins/wordpress-link-directory/captcha.php on line 104