Coolscan 5000 with SF210

We installed a Super Coolscan 5000 ED and SF210 feeder to a P4 PC with plenty of memory, CPU speed etc. Every slide we scan generates a picture on screen that is way too dark and we have to turn the brightness up to 85% approx before we get a half decent view. We're talking to Nikon but not getting very far and wonder if perhaps the kit is faulty. The kit itself is new from Nikon distributor and we've had it for about a week. The software is way too complicated at the moment to know all the tweaks etc but even on default settings we get a rubbish picture. We get the same with the single slide holder fitted. We also are unable to use auto scan, the software returns us to the desktop and we get messages saying that there is a hardware error. We desperately need this to work as we have a total of 50,000 slides to scan, not all right now, but we have to send a fair number off to the publishers and we have a tight deadline.
Apart from shipping it back to Nikon does anyone have any ideas.
Thanks
Lloyd

pc download to true 48-bit color