Does it only happen on Live365.com? If so, it's a website problem. Try one of these ad-blocking add-ons to help:

• AdBlock Plus
• uBlock

I've only noticed it on Live365.com, but it's the only ad-heavy site I leave up for long periods of time.

I guess I'm wondering if it *can* be site-caused, or if it's inherently a Firefox bug, and how to tell.

Is it possible for you to post a screenshot of the ad(s)?

Sure, for what's it's worth. Here's a screenshot of the Live365 page that accumulates all the ghost windows. At the current time there are 210 ghost-windows; 132 of them are cdn3.doubleverify.com/t2tv7.html. Memory usage is 2.165.67 MB and climbing; system is stuttering like crazy. I've saved a memory report but don't see any way to upload it.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

The problem happens the same way in safe mode (extensions disabled by safe mode). Also the same with or without hardware acceleration enabled.

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 that 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

Ran MalwareBytes, Windows Safety Scanner, Windows Defender, AdwCleaner, TDSSKiller, SuperAntiSpyware, Spybot. AdwCleaner reports "HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings[ProxyOverride] = *.local", but it always comes back (apparently a common issue). SuperAntiSpyware reported and removed Rogue.Component/Trace.

Scans are clean now. Problem still occurs. Currently have 222 ghost-windows.

Can you screen capture where these 222 ghosts windows are showing. How do you know you have 222 ghost windows?

The ghost-windows are reported by about:memory. I have memory reports showing them, but I don't see how to upload files. I'll take a screenshot after I reproduce it again.

I'm still curious as to whether this is definitely a Firefox problem or if the web site can be blamed for ghost-windows. Is it definitely one or the other or could be either?

Here's a screenshot after the Live365 listening page has been up for a half hour or so. Over time the number of ghost-windows will climb to a large number, along with memory usage.

And a few hours later. Now there are 41 ghost-windows. This will continue as long as I keep that page open, until I run out of memory or close the page, whichever comes first.

See:

• http://mxr.mozilla.org/mozilla-release/source/dom/base/nsWindowMemoryReporter.h#81

Thanks for the reference to source, but I don't have background to understand any of that.

I just want Firefox to stop leaking memory until it hangs! Is this a Firefox bug? Am I in the right place to report a Firefox bug?

I checked one of those likes out and stuff came up as browser hijacker. You may need to scan computer Malwarebytes and other virus and scanners. Then you might want to add

Adblock Plus :: Add-ons for Firefox https://addons.mozilla.org/en-US/firefox/addon/adblock-plus/?src=ss

and

Ghostery :: Add-ons for Firefox https://addons.mozilla.org/en-US/firefox/addon/ghostery/?src=ss