Poll has stopped working?

Hi all.

I've been using Advanced Poll 2.02 for quite a while and have had no issues.

However I've just noticed that the poll is not displaying any results now...it still displays the poll question/answers but if you try and vote or click to view results the following error appears:

Warning: main(./booth.php) [function.main]: failed to open stream: Permission denied in /home/foldername/public_html/poll/popup.php on line 7

Warning: main() [function.include]: Failed opening './booth.php' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/foldername/public_html/poll/popup.php on line 7

Fatal error: Call to a member function on a non-object in /home/foldername/public_html/poll/popup.php on line 17

I have not made any updates to the site and have got no idea what has/is causing this.

Anyone able to suggest anything?

Thanks