functions.php error message after sign up

Can somebody assist me to solve this error that appear after user has successfully register and create new blog on my website (http://blogspace.pro) here is the warning message and i have also attached the screenshot of the error message for more details..
Warning: fopen(/home/blogspac/public_html/wp-content/plugins/tag-feed/tag-feed.php) [function.fopen]: failed to open stream: No such file or directory in /home/blogspac/public_html/wp-includes/functions.php on line 4452

Warning: fread(): supplied argument is not a valid stream resource in /home/blogspac/public_html/wp-includes/functions.php on line 4455

Warning: fclose(): supplied argument is not a valid stream resource in /home/blogspac/public_html/wp-includes/functions.php on line 4458

Warning: fopen(/home/blogspac/public_html/wp-content/plugins/tag-feed/tag-feed.php) [function.fopen]: failed to open stream: No such file or directory in /home/blogspac/public_html/wp-includes/functions.php on line 4452

Warning: fread(): supplied argument is not a valid stream resource in /home/blogspac/public_html/wp-includes/functions.php on line 4455

Warning: fclose(): supplied argument is not a valid stream resource in /home/blogspac/public_html/wp-includes/functions.php on line 4458