Wow...
Thanks so much Wo3Dan. Turning off the 'Use hardware acceleration' really became the solution of my problem which I've experienced for months.. Thanks a lot, and you've helped not just me but also the whole forum members and readers.. Now it has become normal and I really appreciate your help. You might be created to help people who's in trouble, like superman.. haha.. 
Thanks again... 
No, it's not about colour, but selected or clicked surfaces. The selected (highlighted) surface will be the surface at the back of the clicked surface. But there's no problem with selecting lines or edges. My pc's specs is also good enough to support this software. I use AMD Athlon X2 5200+ 2.61GHz, Gigabyte ATI Radeon HD 2600 Pro and 2GB DDR2 667 RAM. I thought it was the RAM problem, but when I add 1GB more, the problem wasn't solved..If you've ever faced this problem and were successful to solve it, please share with me and the readers.. 
Hello forum members..
I'm having a problem when I select most of the surfaces in my sketchup models. It also occur when I'm trying to paint those surfaces. The problem is, when I select a surface, the surface that I've clicked is not highlighted (selected), but instead, the surface behind it (blocked surface) is selected. Can you explain why, and help me to overcome this problem? Thank you. 