Strange user switching behavior

I'm not quite sure what is going on here, but on a site I'm building w/ Drupal Commons (D6) clicking on certain URLs (within the site) are causing my logged in user to become the admin (user 1) user.

Can anything think of what might be causing this? A permissions issue maybe, something in my theme files?

I'm new to Drupal, so that isn't helping much, but this certainly isn't a very secure issue to have on a site.

Any suggestions are appreciated.

Thanks,
Jerry