odd pop-up appearing at startup

Hi all,

When I start my PC up I have an odd pop-up appearing on the bottom left of my scree, just above the start 'circle'.

It's there for a very brief second - in fact I don't get the chance to read anything on it. It's a narrow grey bar with something written on it, quite short and looks as if it's very old-school. I thought I saw a large 'X' at the end of it. It reminded me of the top from an old minimised window of some sort.

I have Malwarebytes, run regular scans and don't click on links from dodgy emails or file share. So I wonder what it could be?

Sorry I can't be any more descriptive. It generally appears once the icons on my desktop 'blink' after the desktop has initially loaded up.

any ideas - sadly my google searches haven't turned anything up as my terms aren't very specific on this!

cheers - I'll give the above a go.