Checkout issues in 1.2.7

I have a bad problem with checkout in release 1.2.7. I can't upgrade to 1.3 for several reasons. So I must solve it on 1.2.7.

The issue:

• checkout step 1 does not report the delivery options and the "continue" link is a redirect to step 1 again.
• the checkout some times works. Some times not. I tested it on IE / Firefox /opera and the result is mostly the same: sometimes works, some times not. I can't get the logic of the bug.

My settings (includes/configure.php):

...
define('USE_PCONNECT', 'false'); // use persistent connections?
  define('STORE_SESSIONS', 'db'); // leave empty '' for default handler or set to 'db'

  // The next 2 "defines" are for SQL cache support.
  // For SQL_CACHE_METHOD, you can select from:  none, database, or file
  // If you choose "file", then you need to set the DIR_FS_SQL_CACHE to a directory where your apache 
  // or webserver user has write privileges (chmod 666 or 777). We recommend using the "cache" folder inside the Zen Cart folder
  // ie: /path/to/your/webspace/public_html/zen/cache   -- leave no trailing slash  
  define('SQL_CACHE_METHOD', 'database'); 
  define('DIR_FS_SQL_CACHE', '/home/httpd/vhosts/ghiraldin.it/httpdocs/cache');
...

I get some improvements in behaviour changing sql cache method from file to database. Previously checkout does not work on relogin (all browsers) but it worked on instant registration (IE not!).

My Server configuration:

httpd	2.0.40-21.11 
mysql	3.23.58-1.9 
php	4.3.2

Someone could help me? I really need it!! Please!
:cry: :cry: :cry: :cry:

The URL to see the problems?

Thanks so much for the answer and sorry for my error...
I solved the issue: I doscovered that there was and error upgrading from 1.2.6 to 1.2.7. Some files about the checkout were not overwritten and there was the issue.

Thank you again!