PC started to have random freezes?

[CrazyMarijn]

PC started to have random freezes.
I have no viruses, no errors in my drives
but when it happens task manager says my Disk usage is at 99% but on that time max 10 processes are just using 0,1 MB/s..

 

[WyomingKnott]

Disk usage at 99% sounds like the disk is FULL. No space to write new stuff, computer hangs.

 

[CrazyMarijn]

But how can I see what is using so much?
Since it says 99% but all the values of the applications stay around 0,1