This problem looks very familiar... so I'll add to this thread rather than start a new one.
Same issue - 500 internal server error. LAMP installation. I have physical and root access to the server.
Same server is running a BuddyPress site on a different domain. It is working properly.
I can get the wordpress/license.txt file to display on the broken site. If I try the index.php I can see the hard drive light illuminate essentially until the browser times out. Top shows apache using all the cpu cycles when this happens. I can access a phpBB3 installation on the broken site without any issues.
I checked the database with mysqlcheck and noted no errors.
Plenty of drive space.
I can't find a php error log anywhere...
Site is http://www.nanson.org (www.nanson.org/wordpress)
Any suggestions of what to check next??