Import issue using CiviCRM 1.9 and Drupal 5.6 ...

Hello! I'm experiencing issues with the import functionality with CiviCRM 1.9 and Drupal 5.6 running on PHP 5.25. When I try importing it lets me upload the CSV file and map my data fields. Then when I start the import, it gets to about 40% and then stops. I get the following error:

We encountered an unknown error: [object Object]

I'm also getting memory limit errors, but I've tried increasing the memory limit to 100M in the PHP config and it doesn't fix the issue. Here are my PHP settings:

max_execution_time 3600
max_input_nesting_level 64
max_input_time 200
memory_limit 100M
post_max_size 8M

I'm running Drupal 5.6, MySQL 5.0.45, and PHP 5.25.

[b]Now it's working for me on another site I'm running the following on (without issue):[/b]

Drupal 5.7, MySQL 4.1.22, PHP 5.0.5

On this site I don't get any memory limit issues. When I look at the PHP info, I don't see memory_limit listed on this one. I've got the following listed:

max_execution_time 30
max_input_time 0
post_max_size 8M

So this is weird! Is this a PHP or Drupal issue? Do I need to change my version of PHP or Drupal on the site I'm having issues with? Not sure what else to do??

Please suggest! Thanks!