Netstumble.com PHP script not working after upgrade to php 5.2.x

[EM @MAJ.com]

I manage Netstumble.com to provide WHOIS History Check of your domain name for free. After upgrading the PHP script to version 5.2.x the script is not working anymore. I can't figure out what's going on. I know it is the PHP upgrade issue. It stop working after the upgrade to PHP v 5.2

For example, to check the dnforum.com domain name in:
http://www.netstumble.com/whoishistory.html

After hitting [Enter] to check. It will pause for a few seconds (10-20 secs), then display the results and added to the database.

but after the upgrade to PHP 5.2, it is just a blank page, and nothing added to the database. It seems the scripts can't understand the form entries.

Help me solve this issue.

Thanks in advance.
Em