We can't know. We know nothing about your comp, your render settings, your system and not even your version of AE. Also provide screenshots to illustrate your problem.
When you say, "lost its way and drop off", do you mean it animates differently or do you mean it just disappears completely?
If it just doesn't show up in the render, you've set it as a guide layer. Turn that off.
If it animates differently, we need much more info as Mylenium says.
Here's a guess: when you're previewing, you're not looking at the Active Camera.... which is the ONLY way AE will render. And no, you can't turn your Custom View into an Active camera... you have to make one.
And great guess Dave! Thank you!
Apologies for the previous lack of info, it was a student of mine and unfortunately I didn't have time to properly look at what he had done / get any screenshots. But indeed he was looking at a custom camera.
Cheers! Problem solved.