[Interest] tiny fonts in linux

[Rollastre Prostrit]

First of all, excuse me. I bet this has been asked many times. I 
searched the answer without success, however.

In a kubuntu (12.04) my own applications I write with QtCreator (2.4.1) 
and Qt (4.8) are suddenly displaying tiny fonts and they weren't earlier 
today. They are so small that it is not possible to read them. Does 
anybody know what can be happening or how it is fixed?

btw: don't know if it related, but Google Earth has done so (I mean, to 
show tiny unreadable texts) since the beginning.