Scrambled text when viewing some PDFs

Hi,

We are having a problem with one of our users getting text swaped with random and scrambled symbols in some PDFs. The problem seems to get temporarly fixed by logging out and in on the server but it keeps coming back.

I've tried running repairs and updating to the latest version. I have also tried changing rendering, layout and zoom, resolution and "Use local fonts" setting but neither have worked.

Does anyone have any ideas what could cause this?

I attached an example of what it could look like when the problem is occuring.