There are a few phpbb3 bridges for Drupal out there, can you tell us which one you're using?

Note - If you're using the one by vb (That's the developer's Drupal username), then you won't get much support. He's very talented, but he does stuff at his own pace / leisure. His bridges aren't perfect (This includes SMF), you'll have to do some minor tweaking to get it fully functional.

(I can't tell who's module you're using, I don't use phpbb3.)