Strange problem on my laptop, character disappeared sometimes

hello everybody, I got a strange problem, and it only occured on my laptop, when I tried same program on other PC, it seems very well.
in my 3D program, the character sometimes got dissappeared and reappeared again when the chase camera move.
and another problem is that some character model cannot see the material, just a black region
I want to know why this happen and how to fix this kind of problem

what are the specs on your laptop, and what are the specs on the other PC you tested it on?

laptop: Windows 7 with service pack 1
CPU: Inter® Core™ i5-2430M CPU@ 2.40GHz 2.40GHz
RAM: 4.00GB
OS: 32bit windows
GPU: Intel® HD Graphics 3000 and NVIDIA GeForce GT 635M

PC: Windows XP
CPU:Inter Core™2 Duo E7500 2.93GHz
OS:32bit windows
GPU:NVIDIA GeForce 3100