I've just downloaded neXt on my Mac (running OS X 10.10.5) and when I try to use some of the downloaded sceneries the software doesn't respond and I have to restart my Mac. This happens just with some sceneries: Airrace LED, Airrace Bexbach II and JR Canyons (I didn't try them all yet). Whereas with other sceneries it works ok: White Horse flying club, Nightfly and MBG mauchenmuehle. Could it be a problem with the graphic? I have an NVIDIA GeForce 8800 GS 512 MB.
that's because your Mac has not a gamer graphic card. Then you cannot use the X3D sceneries. I guess you can load them when you reduce the window size to 1280 x 768. And then you should open the graphics tab and reduce in the bottom area (expert settings) the details and so on.
Thanks a lot for your prompt reply. I've reduced the window size and the details resolution as you suggested but I still get the same issues. My graphic card it's probably too obsolete for those sceneries. Thank you anyway for you help!