I have a SharePoint 2010 site with anonymous access enabled. There are PDF and word documents on the site. Recently users, whether they are logged in or not, are being prompted when attempting to open documents.

When opening a PDF a popup window displays the custom FBA login. If the user enters username/password the sharepoint site opens in the popup window and adobe reader is open in the background. The PDF never opens.

I am not sure why this started happening recently. I had a FBA login problem after adding an additional IP address but figured out the new IP was being blocked by the firewall. Opened up the firewall and fixed that problem. I don't think the new IP address is related but I am not sure.

Thank you