Please look for it in Tools > Addons > Extensions, try disabling extensions that have "Ask" or "Ask.com" in their names, restart Firefox, check for the issue.

Thaaaannnks. It was so irritating.

Please click the Solved It button next to the answer that solved your Firefox support issue (it appears when you are logged in), so this thread gets marked as Solved to help other users who may have this same problem.