failed to open stream: Permission denied

[johnsteins]

In our website design I was wondering if anyone has ever seen an error like this at the bottom of our website at http://www.sonnarinternet.com

Here is the copy of the error at the bottom of the website:
Warning: fopen(/home/sonnarin/public_html/components/com_sef/cache/shCacheContent.php) [function.fopen]: failed to open stream: Permission denied in /home/sonnarin/public_html/components/com_sef/shCache.php on line 112

I have tried changing permissions on this file but to no avail. We are using Joomla and a component called sh404SEF

I did a search on Google for com_sef/shCache.php and came up with many other people having the same issue.

Anyone know what could cause this?