Invisible Internet Explorer

[#1]

Last week I saw a machine that would run an invisible second instance of Internet Explorer whenever Internet Explorer was started.  There was nothing to see on screen but it showed up in Task Manager.  It seemed to be cycling through a series of web sites, some of which had audio which made the whole experience rather spooky.  I tried a malware scan (AVG) and a rootkit scan (TDSS Killer, Gomer) but nothing was found.  By the time I had uninstalled some unidentified programs that seemed to have arrived with a Flash Player 'update' and restarted the computer the problem had gone away but I could not see how the trick was being done.  Has anyone else encountered anything like this?       

[#2]

First guess would be that something malicious had installed an "add-on". They usually appear as toolbars in the UI but it is possible to make invisible ones. Well done on removing it, they definitely don't make it easy!

[#3]

I'm running a single instance of "Invisible Internet Explorer"!  
Indeed, this post is made from it.
None of my security softwares have picked up anything untoward - Malware bytes; ABP; NIS; System Mech Pro.

[#4]

Funnily i aint got IE installed , but Ccleaner still cleans its cache 

[#5]

IE? I haven't used that piece of crap in years for regular browsing. Do people actually still use it?

[#6]

If you have not used Internet Explorer for years you would not know that the current version really isn't that bad.  Firefox waxes and wanes as it brings out a new version about once a fortnight.  Chrome has all sorts of vulnerabilities, not least a registry setting that can be abused to block further updates.  But all that is off-topic.
I have found references going back over a decade to a 'feature' of internet Explorer that permits an instance that is not visible on-screen but I cannot tell if this still exists in current versions.  But I suppose recent experience proves that it must still exist.  I was hoping somebody might know something about it.   

[#7]

Quote from: 7up

Do people actually still use it?

Not out of choice, since getting a chinese IP camera, I've had to use IE and an ActiveX extension (remember those?? Massive vulnerability for IE!!) to access said camera's web interface to set it up, but it's a one-off thing, set the camera up, shut down IE, let Genius vision do the work of recording...
And I'm expecting an onslaught of accusations of being geeky and nerdy again, but PaleMoon's a great alternative, it's Firefox that's been fixed so doesn't break down every 5 minutes or flood your RAM with a memory leak that Mozilla has still yet to fix, uses FF plugins and addons (at your own risk of course), has the original FF layout before they made it look all goofy, and just works, plain and simple...
AND, it's even been de-googled (uses Duck-Duck-Go for it's search engine) for those who care about such things...

[#8]

I use it to view my webcam because the plug-in available is not compatible with Waterfox.

[#9]

I agree that IE is now not really bad at all any more.  I still use Chrome mostly, but IE fairly often (checking compatibility, visitor with a different gmail login, ...)
Had you tried Malwarebytes Antimalware. https://www.malwarebytes.org/
There are lots of undesirable behaviours that are not strictly viruses that standard AV don't tend to pick up, and that Malwarebytes does.
It doesn't interfere with regular AV; well worth running if you have odd popups, search engine hijacking etc, or just one a month just in case.