Activated MarketPress plugin now can't access website, any ideas?

Hello,

Working on http://www.scareylures.com, just uploaded and activated MarketPress (latest version). But, right after I activated MarketPress, it's almost as if the website (the WP installation) just disappeared. Now, all that shows on the page is a blank white screen with an empty HTML body. I can no longer get to the WP login page either.

Current theme in use was the 2010 WP theme. There was another shopping cart solution activated at the time, not sure if that would be related or not with a possible conflict. Don't recall the name of other shopping cart solution now that I can't log back in.

Have you heard of this before? Could a plugin cause that?

I'm going to be checking the hosting account as well once I get access to it.

Thanks,
Mike