Dave-So seems to have made more points I'd like to address than anyone else since als tI was here so.... "what are the known programs that don't work with XP and Nvidia ????" I'm always deeply suspicious of anything that has a lot of updates - it seems to me that, by definition, those items were released in a poor state. While CL with P5 seems that way at present, I've had years to experience watching video card manufacturers churn out driver after driver - often having a beta and an older "WHQL" driver available for download, back before they even started archiving old drivers... and just look at the number of "updates" to ANY version of Windows since 95 - it's horrendous! But I was on the subject of graphics drivers - these I've seen updated time and time again often (as with many types of software fix) introducing more problems (or re-creating old ones). It always amazed me that video card vendors bothered paying Micro$oft for it's WHQL certification since this didn't seem to mean the drivers actually worked... but limiting oneself to known OS/video card/application issues is potentially unhelpful. the video card vendor usually knows of at least some issues - that's why they keep coming out with fixes! In THEORY CL may have believed that by sticking to old video card techniques - "doing 3D the hard way" (but using existing code) that they were avoiding problems with new cards and techniques which, due to not being fossilised, were not as reliable. They may even be right, except that it's probably getting more and more irritating for video card vendors to include backward-compatability to such an old method... "Another driver issue...everyone offering advice on drivers makes the statement "make sure you have the LATEST drivers"...but is that actually the best policy? ... Did you ever think it may be more beneficial to go to the Nvidia driver archive and try an OLDER driver package???" This hasn't passed me by, but... that the majority of people who actually benefit from the idea of driver or OS updates are generally quite intent that CL are "to blame" (it amazed me when some chap found that doing a Windows updated fixed P5 considerably - I'd not thought of trying to run a Windows OS without huge gobs of bug fixes in years, so found the idea of an untouched installation...bizzarre!). Given such a fixation on CL, to suggest the vast slew of things that MIGHT help stability is a step somewhat braver than I've been inclined to take. At least, in one go. Especially as some of the "correct" steps to take to diagnose the culprit, in cases, are beyond your average punter - who may not have spare hard drives, alternate videoc ards etc. etc. and have the TIME to take their system back to basics and build it up, over time, watching carefully until somehting they add appears to suddenly decrease stability. Spit "What does bother me greatly is the lights in P5 though. I depend on DAZ's complex globals so still do most of my rendering in the ProPack. Sigh." I've heard P4 lights cause issues in P5 too... I wonder if saving light sets as P5 ones (perhaps having changed them to raytrace and back or somesuch - "touching" them enough to make them P5 lights) might be a potential aide?