Joomla, Virtuemart site BROKEN, Help Needed ASAP

I need a help with a small Joomla website, with Zencart already installed. The website is currently down with a php error message. ---- Warning: array_key_exists() [function.array-key-exists]: The second argument should be either an array or an object in /home/corpinc/public_html/libraries/[login to view URL] on line 139 Fatal error: Class 'JRequest' not found in /home/corpinc/public_html/libraries/joomla/[login to view URL] on line 33 ============== The focus of the project is to troubleshoot and resolve the issue on the site. Joomla 1.5 and ZenCart are already installed and ready to go on server. I would like to have this project completed ASAP, as this was a live site Thanks to all bidders. Len