Activation of theme makes site go blank

[erickjam]

I hope someone can help out here...

site is http://emcdental.com/blog (current theme is iblog2)

Just purchased pro pack yesterday, and went to activate on a blog that has 156 posts already, once I activate the theme, the site goes blank. All I see is the url in the title bar.

All theme settings are defaulted.

Here are the plugins I have Active:

Akismet
All-In-One SEO
Featured Content Gallery
Google XML Sitemaps
Page Link Manager
Sociable

I also tried to activate Corporate, and Streamline, but I get the same blank page.

Wordpress Default theme works fine.

I have tried with all plugins deactivated and I get the same blank page.

Please help!