Allan, thanks for the reply, maybe a silly question, why would advance rendering be ok and basic rendering a problem, I thought that it would be the other way around. I guess that if basic render continues to be a problem, one can always use advance rendering even though some what slower.
The simple building in the second post consists of walls, automatic fitted roof and standard windows, so it should have rendered ok.
I played around with your solar HWS in the first image, lifted it above the roof, turned off the filter and even deleted it, no joy. Program still crashes.
If there is a corruption problem in the drawing, why would it cause the TFP to crash. (ie TFP completely closes down). I would have thought that if there was a problem ,render may not work, but the TFP should not crash. Maybe I need to take this up with IMSI.