Little squares everywhere
It is a FONT problem by the sound of it.
Each square represents a character that your system does not recognise. You will notice the same effect if you try to view kanjii characters on most systems.
Have you removed any other software recently? - This causes most problems.
You may have the system/software set to display a non existant font.
You can also cause the same problem by trying to force software to read a non-compatible document.
Just food for thought to get you started on the million & 1 things it could be.