Problem! - Incorrectly-displayed fonts

[vipii]

Hi,

Recently I installed some fonts on my MacBook-Pro. (Mac OS X Lion - 10.7)
And since a few days my PDF's are having other fonts. (I use Preview to view my PDF's)

How can I get back the normal Font for my Preview?

A screenshot of the problem:

 

[Detrius]

Run Font Book diagnostics to find the bad fonts. *Delete* them. Then clear the font caches and reboot.