Re: changing host name, login problem ?

Platonides wrote:
 > Check that php is able to save the session files. session.save_path must
 > point to a writable directory.
 > http://www.php.net/manual/en/session.configuration.php#ini.session.save-path

Thanks for the hint.  This is exactly what the problem was.
The session save_path directory did not exist on the new machine.

We also discovered that an upgrade of PHP from v5.0.4 to v5.1.6
required a change in LocalSettings of memory_limit from 20M to 80M:

# If PHP's memory limit is very low, some operations may fail.
ini_set( 'memory_limit', '80M' );

This may be due to changing from a 32-bit machine to a 64-bit machine
where they php system uses more memory for page construction.

--Hiram