Blank Error Page

I have a WordPress 3.6 site with WP E-Commerce 3.8.12.1 and I’ve been experiencing a strange problem lately. The problem is that when I’m updating the site, pages or products, etc. I eventually get a blank screen with an error message that says only “error” I looked at the source and there’s nothing only the text saying “error”. When this happens the backend and frontend are affected and I have to wait about 30 minutes or so and then refresh the page and it starts working again. Any ideas?

Thank you.