500 Server Error on New Installation

I know I’m not the first to have this problem, but looking and trying all other previous fixes doesn’t seem to work.

Fresh installation. Hosting by Fasthosts with PHP 5.2.5 and MySQL 5.

All done exactly as per the WP guide. Trying to run the install script (in fact, any of the WP scripts) returns a 500 error.

Phpmyadmin works, as does the short phpinfo script that Fasthosts uploaded as a test, so what gives?

Errorlog shows:

[Mon Oct 19 11:25:03 2009] [error] [client 84.92.46.51] (104)Connection reset by peer: FastCGI: comm with server “/var/www/fcgi/php-cgi” aborted: read failed
[Mon Oct 19 11:25:03 2009] [error] [client 84.92.46.51] FastCGI: incomplete headers (0 bytes) received from server “/var/www/fcgi/php-cgi”

An identical installation on my localhost some months ago (latest upgrades and all) worked just fine.

Any advice gratefully received.