hi john, it is highly unlikely that the mozilla maintenance service would cause data usage - its only job is to provide elevated rights for the firefox update process, but doesn't open any connection to the internet... https://wiki.mozilla.org/Windows_Service_Silent_Update

how did you determine it was the mozilla maintenance service causing the issue?

Are you sure no one else is using your internet? WiFi without passwords can be used by others.

Many programs 'phone home' to get updates, but I don't think they would use that much net.

After I removed Mozilla maintenance the data lights settled down and the tracking program also showed that. This morning I checked, I was wrong. Data is still being used when I'm not using the PC. We live in a rural area and no one is closer than 1000 feet. I have a password installed and my guest accounts are turned off.

I was going by the date the data usage went out of control. I cannot go any further back than the day I upgraded from 12G to 16G. We did this to connect Echo Dot to set up for a Christmas present, which we did give away. We always used up our 12G before the end of the month but only a few days ahead of time. That first night of increasing to 18G, 6G was used in hours. We assumed it could be the Echo Dot and shut them down then installed them at the recipients house.

I can't seem to find the culprit, it seems to use data when we aren't online. Windows 10 also upgraded the same time, I can't restore to an earlier time.

When you are not online, unplug the modem.

Set your firewall to lock out everything you don't know what it is.

Are you using a wireless connection to the router and is that connection secured properly?

It is possible that others have hacked your modem.

Also do a malware check with several malware scanning programs on the Windows computer.

• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

"We did this to connect Echo Dot to set up for a Christmas present, which we did give away."

Is it possible that some software was automatically installed on your PC when setting up that EchoDot? Sorry, I don't know exactly how that type of device works, but do understand the concept. If Firefox is being blamed "something" for that device had to go thru that PC to get Firefox "involved". You may have an application on that PC that is using Firefox to "phone home" for updates, for data, or whatever. And that may be causing your problem with excessive data usage.

Check the Windows Control Panel > Programs & Features (or whatever that's called on Win10) and look for an Amazon DotEcho program or anything else installed on the day you set up that device