Login error while testimonials widget premium is active

Hi,

I am getting wp login errors when the testimonials widget premium plugin is active. Making it inactive fixes the issue. The site is smarterghost9.com.au

The versions are: non P Version 2.12.8 P Version 1.13.1

The errors are:
Warning: session_destroy() expects exactly 0 parameters, 1 given in /home/smartg9/public_html/wp-includes/plugin.php on line 406

Warning: Cannot modify header information – headers already sent by (output started at /home/smartg9/public_html/wp-includes/plugin.php:406) in /home/smartg9/public_html/wp-includes/pluggable.php on line 876

Thanks

http://ww.wp.xz.cn/extend/plugins/testimonials-widget/