Sry about my bad eglish I m testing both Nod32 V3.0 and V 2.7. Obviously there are different heuristic engines in them ... I installed "Startup Faster" and V 2.7 detects "probably a new Virus" with heuristics and refuses to install . V3.0 didn't detect anything. A Few Weeks ago i had the same effect with a new Variant of a Beagle.LI Worm. While V2.7 detected it, V3.0 dind't again.....( meanwhile V3.0 detects it also). Are there great diffenrences in the SCAN engines between V3.0 and 2.7 ?