Solved Rogue window appears bottom left periodically

[treehouse]

Hi guys, just wondering if anyone can identify what this is (attached) - a window keeps appearing once or twice a day, usually when coming out of sleep or booting up. It's apparently disabled and not available to window commands, except it can be dragged elsewhere (when it becomes just the empty title bar). It seems to happen while the system is undergoing various system checks and is maxed out for minutes. It started after I installed Avira (previous to this, I was fixing some other issues with weird window behaviour as per this thread), which I fixed, but then I installed Avira. Avira finds nothing. Malwarebytes finds nothing. Now, Webroot finds nothing (I'm going to uninstall Avira, so maybe that'll fix it).

I've started trying to catch it, and might install a window spy or something (like Autohotkey), but just thought someone might know what it is...or how you'd go about tracking down its identity.
Cheers
John
ETA: Ignore the text, by the way, it's just off a web page - I just cropped it a bit wider and higher to give some context, like the taskbar.

 

[treehouse]

I uninstalled Avira using Revo and installed Webroot AV. Also found a leftover McAfee file doing my usual Ccleaner routine. Whatever it was has gone.

 

[lehnerus2000]

Process Explorer

For future reference, Process Explorer has a tool that you can use to identify the process associated with a window.

You can download it from here:
https://docs.microsoft.com/en-us/sys...ocess-explorer

​

It's a portable program (i.e. it doesn't install and you can run it from a USB stick).

1. Run the exe file (or unpack the zip file and then run the exe)
2. Drag the Crosshair icon over the mystery window and "drop it"
3. Check which process is highlighted

​

My screenshot shows that I dropped the Crosshair on the Pale Moon window.