Joomla site not working after migration to new CCGI Hostopia platform

[#1]

Hi, just looking for some tips here. I have a very old Joomla site (1.0.11 circa 2006, I believe - the configuration.php.dist that is still lying around has 2006-08-28 in its header).
I have made the changes for the database in its "configuration.php" but trying to access it gives a blank screen in the browser and 500 error in the access_log.
I don't know what I should look at. It worked before the migration and, according to the New CCGI FAQ, it should work. I have not changed any file permissions or anything else because the FAQ indicated this shouldn't be necessary ("your files and scripts should continue to work after the migration").
I have written a test PHP script to confirm the database credentials that I am using are correct and also that the data is in the database.
Can anyone offer any guidance please?
(I realise its a very old version of Joomla and I don't plan to upgrade it because it's just an archive of old content. It would be nice to get it working if I can).
Thanks.

[#2]

Error 500 usually means a misconfiguration issue, though usually an error page results from that rather than a blank screen. Did you run that script checking database access from the Joomla directory so any .htaccess there would apply?
It's possible that version of Joomla isn't compatible with MySQL 5.5 (Plusnet CCGI had MySQL 4.3). Or possibly it's incompatibility with PHP 5.3 though it must have been OK with 5.2.
Current versions of Joomla require magic_quotes_gpc to be off and having register_globals off is also recommended.;  CCGI had magic_quotes_gpc off.
For starters you could try adding the following settings to /public/.htaccess
[code=for /public/.htaccess]
# turn off  these flags
php_flag magic_quotes_gpc 0
php_flag register_globals 0
# display any PHP error messages
php_value display_errors 1
php_value error_reporting 32767[/code]

[#3]

Thanks for the .htaccess suggestion to allow error messages be displayed. It quickly pointed out that the problem was due to the migration not updating paths in the configuration files. Once I had done this, everything worked, and continues to do so after removing the .htaccess. Much appreciated.
My experience of the migration hasn't been great but at least now everything is fixed. I initially had an empty database and then found that configurations options had not been correctly updated, like this one (which I missed).