Hi there

I am new to this forum and i hate this to be my first post, but i need help with what seems to be a solidworks error.

I have created two assemblies, one is a motorcycle model (very basic), and the other is the road i want it to travel along. The road is 20m long, with three obstructions/ bumps which are extruded curves which are based on the 1-(cos(theta))^2 function. The issue i am having is that when i have the bike travelling down the road (details of forces/ motors/ springs below) if the picture is zoomed out, the bike is visible, when zoomed in (so i can see the suspension movement) the bike assembly goes transparent, apart from a few greyed out sketches on the assemblies. I have made this motion study a few times on two computers to see if it still happens and it happens on my desktop and laptop with multiple attempts. Any ideas would be greatly appreciated. Thankyou in advance. Ross