Google adsense block displaying "The Page Cannot Be Found" error message page

Downloaded and installed the Google Adsense module on Drupal 5.2. Went through the setups using an existing Adsense account that works fine on another website.

After enabling the Adsense blocks and exiting from Administrator role, the Adsense boxes are showing the standard "The Page Cannot Be Found" page. Checked all block and module setups and found no obvious issue.