Unauthorised access/ 4xx errors in Firefox but not in Chrome (using wptdriver)

Few internal URLs (accessed within the company which are based on user profiles ) and https urls run successfully in Chrome. But show 4xx error / Unauthorised message / Untrusted connection in FF. Also it opens a prompt asking user credentials (username and password) each time rather than leading to the actual web page (This loads as expected in Chrome)

Any changes in Firefox settings will help resolve this

Your help is much apreciated