Thank you for your suggestion. I tried to do this, but with the same result. Then I reinstalled the georgia fonts, which shouldn't have been possible, if they were still installed - right?
So, I noticed that there was a difference in the fonts (yes, they look much nicer). However, after uninstalling them again, I can still read greek letters instead of gibberish. I'm baffled. Maybe the Kindle now recognises the greek alphabet, and Amazon never notified us?
Anyway, I guess I'll have to wait and see what happens when -and if- the 2.5 arrives.
Thank you again.