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