Popup blocker may block downloading files as well as also block flash player most of the times and prevent you from opening any external page that will open in a popup form. It generally shows yellow address bar which indicates popups are blocked.
If you are not aware to fix untrusted connection error in Mozilla the read post to know How to Fix Untrusted Connection Error in Mozilla Firefox. But to remove pop up ads from Firefox follow methods mentioned below in the blog to remove pop up blocker from Mozilla Firefox web browser.
METHOD1: DISABLE POP UP BLOCKER
Step1: Open Mozilla Firefox.
Step2: Press control + shift + A to open add on panel.
Step3: Now click on Extensions and search for pop up blocker.
Step4:If not found go to step5orIf found click on the remove button and uninstall the extension and restart the browser.
Step5: If not found then click on plugin tab.
Step6: Search tab for pop up blocker.
Step7: Click on the remove option found after opening the plugin or you can delete the plugin.
Step8:Clear history and cookies and restart browser.
METHOD2: DISABLE POPUP BLOCKER IN SETTINGS
Step1: Restart Mozilla Firefox.
Step2: Click on the horizontal lines at the top in the right hand side.
Step3: Now click on options and select content option.
Step4: Now uncheck Block popup windows, press ok and exit.
If after fixing pop up removal issue you are still facing the problem follow second method in the blog. If after following the method you are still getting same issue again contact browser support. To get in touch with Mozilla Firefox support phone number call toll free +1-888-311-3841 and get online help from certified professionals.