[eluser]Unknown[/eluser]
The solution for me was to get PHP/Apache recompiled.
Do you know if media temple had any maintenance lately?
Did it work earlier? If so, probably something happened over at media temple.
The reason I had to get PHP recompiled was because we upgraded from MySQL 4 to version 5. So when I was trying to connect to the DB it failed somewhere in the CI code. And it turned out it was something wrong with PHP, and it needed to be recompiled.
Try disabling/putting false values in your DB config and see if that makes the site load/throw a different error/give a clue what the problem could be.