Server Crash

I had used this plugin for 5 month.
in two last weeks, we had 503 error in site.
We enabled the WordPress Debug, and we get a lot of errors depends to SEO SMART LINKS
there is some examples:

[18-Jan-2016 01:27:03 Asia/Tehran] PHP Notice: Undefined index: قالب in /home/xxx/public_html/wp-content/plugins/seo-automatic-links/seo-links.php on line 400
[18-Jan-2016 01:27:03 Asia/Tehran] PHP Notice: Undefined index: قالب امجد in /home/xxx/public_html/wp-content/plugins/seo-automatic-links/seo-links.php on line 400
[18-Jan-2016 01:27:03 Asia/Tehran] PHP Notice: Undefined index: قالب امجد in /home/xxx/public_html/wp-content/plugins/seo-automatic-links/seo-links.php on line 400
[18-Jan-2016 01:27:03 Asia/Tehran] PHP Notice: Undefined index: پوسته in /home/xxx/public_html/wp-content/plugins/seo-automatic-links/seo-links.php on line 400

https://wordpress.org/plugins/seo-automatic-links/