The source folder was called qtcurve
So I did what most people would do, I deleted it. But it came back. So I deleted it again. And it came back. Again. So I Googled it so see what caused it. Google says possibly Linux. As I'm a Windows XP user who has never even SEEN Linux I say not likely.
So I have to use my memory (not easy for me, my short term memory is TERRIBLE) and try to remember what has been installed or updated recently. Then I remember I've recently updated Quicktime. qtcurve, QuickTime.
Hmmm, suspect.
The alarm bells start going off.
So I Google "Is it safe to uninstall Quicktime"? Turns out its used for Mov files (pretty much obselete now) and Itunes which I don't use. So off it goes. Then the folder comes back.
So I do a more detailed check, bits of Apple software are still lurking. I uninstall all of them, I've already checked I safely can.
And it STILL comes back. So now I'm thinking virus or spyware. So I do a search of my main hard drive to see if the folder exists there too. Several minutes later.
DING DING DING! We have a match!
It's part of ebook convertor & reader Calibre.
So as a very annoyed person I ask on Facebook how to get rid of the annoying little git.
preferences -> look and feel-> interface style-> default.
According to the very nice and very helpful person on Facebook who I apologise to for sounding sarcastic. I was literally about to bin my PC at that point.
So I've followed those instructions & hopefully won't be seeing any more of that folder.
If you have the same problem, hopefully this will help you get rid of it quicker than I struggled to.