This is weird.

Today I opened an excel file with libre office. Suddenly I saw the mouse changed color, and stuck to it was a message in Arabic, which changed every second in a loop. I can actually read Arabic so I immediatly recognized it as Islamic messages praising Allah (including the Takbir).

Here's a screenshot:

At first I thought this was something with the file, but then I saw that this happens with any libre office program (but only libre-office programs), and even when they're open, it only changes the mouse when it's hovering over the libre program, and goes back to normal anywhere else. Also, re-installing did not help.

I tried running software updater - but I got an error where it couldn't load some steam repositories, but that seems like a coincidence:

Failed to fetch http://repo.steampowered.com/steam/dists/precise/steam/i18n/Translation-en_US  
Failed to fetch http://repo.steampowered.com/steam/dists/precise/steam/i18n/Translation-en  

Here's another hint - I tried taking several screenshots of several messages, but they all ended up showing the same message (the one above). Hopefully that means anything.

I should note I haven't installed anything fishy lately, and I hardly ever use libre office at all (I prefer Google Drive whenever I need to work with documents), so I'm really unsure as to how this happened.

Anyway, this is scary. Any help would be greatly appreciated!