Hello groove25, thanks for your fast reply. I am not using any font menaging programs, and I also tried restarting the computer - it didnt help. I also noticed that if I select a text box and scroll down the font selection box in order to see how the text would look like, it shows the troublesome fonts as some default serif font, even though the fonts in question are sans serif. I will try and reinstall the affected fonts as a next step, I hope that will help.
