Vray 1.5Sp5 - Stuck on Prepass

[TutanMark]

Hi! Did non upgrade to 2.0 yet..

I have a large scene (interior) with load of IES and 1 fastsss2 mat. Since last night vray stuck after LC calculation. It say "prepass 1 of 1". It can stays like this for hours.... even using low subd (400) progressive path tracing

Without IES seems better... but i need them...

Any idea?

Thanks!
Marco