Macbook pro shuts down on stuartup

Reinstall Snow Leopard without erasing the drive

1. Repair the Hard Drive and Permissions

Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.

If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.

2. Reinstall Snow Leopard

If the drive is OK then quit DU and return to the installer. Proceed with reinstalling OS X. Note that the Snow Leopard installer will not erase your drive or disturb your files. After installing a fresh copy of OS X the installer will move your Home folder, third-party applications, support items, and network preferences into the newly installed system.

Download and install Mac OS X 10.6.8 Update Combo v1.1.

If the above doesn't work then you've had a hardware failure and should take it in for repair. This could be a hard drive failure or some other hardware breakdown.

The one beep is a ram issue.http://support.apple.com/en-us/HT1547 Try removing and resetting the ram. Also do a pram reset by holding down the command/option/p/r keys while holding the power button down for three chimes.

Glad to hear that. Do you have your original system disks? If you do you could run the hardware test to make sure you have no problems. You could still have a ram problem. Even if it's only one of them. Also read this article to see how to speed up you macbook.http://discussions.apple.com/docs/DOC-6921 You should also check your hard drive per Kappy's post. You don't have to reinstall ,but you should do permissions and check the hard drive .