Hi,

How to see if our hard disk has problem or breakdown or need to repair and etc?

Thanks!

Here's a good freebe: SMARTReporter
As long as you're at it, check your RAM: Rember

Resolving Disk, Permission, and Cache Corruption (http://thexlab.com/faqs/repairprocess.html)

Alsoft's DiskWarrior (http://www.alsoft.com/diskwarrior/) is a great tool to have if Disk Utility fails to repair the startup disk on your Mac.

Disk utility will work as well and it's included with osx. Just verify and repair. If you can't get to your desktop now, it is also on your install cd, under utilities. Also, If your using leopard or earlier I also think applejack is worth installing.