We have set up a members area on our web-site, with login details on the front page to the members area.
When access to the members area in gained, and our PDF documents are accessed, third party advertising banner appears across the bottom of the screen. The advert for Bravenet is ok, not not the other stuff.
OK, you have a members area protected by Bravenet Password Protect (aka Password Gate). That doesn't require you to host the protected pages at Bravenet but if you have then it is down to the hosting level that you have chosen. If you are using the free service then you get third party ads. If you have paid for hosting then all files should be totally ad free and you should raise a ticket if they are not.
Its all a bit confusing at first as the main site is not at Bravenet and without access to the protected pages we cannot see what you have done with that part of the site.