PR - strange. When I view your site in IE, I get the
PR of 5. When I view your site with Firefox, I get the N/A.
Concerning your issue, I would go back to the update that took place over the weekend. It seems that Google was focused on giving more weight to topical links as opposed to just the amount of links pointing to your site.
Your 336 links pointing to your site, are they all using the same anchor text? If so, diversification may help you out on that. Google views identical anchor text pointing to your site as potential spam (had this happen to one of my clients), and will penalize accordingly.