Sketchup model jumps above and below ground in google earth

[Slappy]

Hi everyone,
I'm using Sketchup Pro and Google Earth Pro
I seem to be having an issue with some Sketchup models when I place them into Google earth. I have placed a few models in Google earth before and they don’t have the same problem. The problem seems to be that my models dip below the ground as I rotate around them in Google earth and then pop up again. I can rotate around them and they will completely disappear and as I continue rotating they appear at various levels below and above the ground. Also, each time I try to re- place the model, it never shows up in the exact same place, it seems to be few meters off in one direction or another.

Thanks for any help you can provide.
Slappy