I am having the same issues using IE7. I logged out and cleared all cookies and temp internet files, then closed the browser window and opened new one, then logged back in (front page), no ads on the main page, but going to the forum and logging in (again) I still see ads...no matter what page in the forum I visit. The ads are going even though it shows me as logged in.
I was able to clear cookies and re-login in FF3, with no ads.
Edit: nevermind...I just went back to IE7 and the ads are now gone from the forums area. 
I tried to change my avatar using FF3, but the "Add Image" button wasn't working...it works fine in IE7. Also, I noticed that going to my profile/settings using the link above my avatar on the front/main page took me to the previous version profile (where it only allows 50x50 icons) but using the link above (the gray bar below the search window) takes me to the new version profile.
Once the kinks were worked out, the new forum is great! Thank you forum dev team for the upgrade! 
