No idea, does not turn up around here in anything I can find nor a google search. Is this a file or a registry entry ? If is a file please find it by searching or through CCleaner history I would think. Or next time run CCleaner do not have it delete just scan so can find the path and the file. This holds up for the same thing if it is a registry entry. Need the full key to understand this more. In the meantime please do this : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware to make sure it is not a malware issue. If it is found report back if found as a Firefox issue but do Save the log files and go to one of the Malware Forums if you have issues. Please let us know if this solved your issue or if need further assistance..