I started getting getting 500 Internal Server Error a couple of days ago when I spent the night manually writing 300+ blog entries.
The error log just says:
Premature end of script headers: php5.cgi
I have used Top and killed off all the php5 processes
I upgraded to WP 2.0.7
I deleted all the plugins except wp-cache which was needed. I am using the Default 1.5 theme with no plugins.
I tried the Saved my domain.name on the domain panel - to rewrite the htaccess etc
I tried going back to PHP 4
I can go to the blog Dashboard but the blog home page will not load.
None of the above steps have made the error go away.