Although it's been a while I remember a similar sounding error for when you import a model that has more than 4 points (IE, it's not a triangle or quad). Might be worth checking just to rule out that possibility.
STALKERGB ♪♫ FYI AFK IRL... (Very slow to answer these days...)
Today i found one model, that i can open. I think it's a "memory" problem. But with 8GB, strange
As a rule of thumb, if you require help here, you really need to provide a lot more information and details about what your issue is:
1. What is your vertex/traingle/poly count
2. Is the model Z or Y up (depends on the exports options and/or software used to make it)
3. Is you model made out of quads and triangles? Do you have any ngons?