Hi again. I've been investigating further on these issues and I'm glad to tell you that the HP DeskJet F380 scanning issue was actually about permissions, exactly the bug stated here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=522848
But the SGH-L760V's issue is still open and can't spot any other symptom that may point elsewhere than a bug in the kernel. Cheers!