Multi screen font display problem

Hello, I’m running blender for years.
I work right now with 2.71 on a mac pro 8 core, OSX 10.9.2, 12G ram, with two GC ati 2600xt (old) + ati 5770.
Ive been working on an old 19" fujitsu screen for years on both GC…
I’ve juste bought a Dell Ultrasharp 24" for better color precision and tried running blender multi screen.
The Dell is on the ‘new’ GC and the Fujistu teh old one.

But when I move a blender window in the fujitsu screen the fonts get strange (they transform in small line) and unreadable.
I tried every configuration possible with international font and open GL in blender pref (didn’t restart blender each time though…) without any succes.
If I ask OSX to make the fujitsu the “main screen” (in syst pref) blend is still font blurry…

It dosen’t seems to be driver related as blender have been running on each GC and mono screen configuration but…

Any ideas ?

Thanks

Ok a fresh install of the last version (2.72b) solve the pb.
Maybe some personnal config somewhere bring the mess…

In fact no, after saving the pref, opening an old project the problem shows again…