Unknown space 154GB on a 250GB SSD

I have a problem with unknown space.

It's on the system c:

It's Samsung SSD EVO 850 250GB

WinDirStat lists 154 GB <Unknown>

CHKDSK can't detect any problems.

Although it's a couple month since I bought this computer I haven't used that much.

I'm not a gamer.

Feeling a bit stumped now.

That did the trick.

Now, before marking the thread solved, two questions.

1. Why did this happen?

2 How do I prevent it from happening again?

maxie said:

Was it Acronis that was the issue ? ... If so it creates temporary hidden Files ..

You are reading my mind, no I mean my system. I do indeed have Acronis.

OK, but if they don't disappear they don't seem so temporary to me. Is there a setting or something that can fix this?

maxie said:

This Link may help ...

https://forum.acronis.com/forum/7558

Yes, it turns out Acronis simply don't care so I have to find another back-up solution.

Thank you for kind support, maxie.