We are not notebook forum.Mac OS X Help
Isolating Issues in Mac OS
Troubleshooting: My computer won't turn on
General purpose Mac troubleshooting guide: Isolating issues in Mac OS X
Creating a temporary user to isolate user-specific problems: Isolating an issue by using another user account
Identifying resource hogs and other tips: Using Activity Monitor to read System Memory and determine how much RAM is being used
Starting the computer in "safe mode": Mac OS X: What is Safe Boot, Safe Mode?
To identify potential hardware problems: Apple Hardware Test
General Mac maintenance: Tips to keep your Mac in top form
Resolve startup issues and perform disk maintenance with Disk Utility and fsck - http://docs.info.apple.com/article.html?artnum=106214
Using Disk Utility in Mac OS X 10.4.3 or later - http://docs.info.apple.com/article.html?artnum=302672
Disk Utility's Repair Disk Permissions 10.0-10.6 - http://docs.info.apple.com/article.html?artnum=25751
"Try Disk Utility" (modified from http://support.apple.com/kb/TS1417)
1. Insert the Mac OS X Install disc that came with your computer (Edit: Do not use this disc if it is not the same general version as what you have currently on your computer, e.g. use a Tiger disc for a Tiger drive, not a Panther disc), then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk."