You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

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A post was flagged as Solved Problem. If the problem is not solved, please remove that flag. If you don’t, others that can help may not read this post.

Go to that message, and use the Undo link to its right.

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Firefox is actually designed to contact it's servers upon closing. As for when opening am sure it does the same and also contacts the Extensions you have installed.

I read that some where. As to where can not provide that as can't find it now. It is something will have to contend with but you now know that that is correct.

Please let us know if this solved your issue or if need further assistance.

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