First, shut down the computer, then disconnect or remove any non-Apple hardware: memory (RAM), external disk drives, printers, and so forth. See if the computer starts up without these.
"Breaking glass"
The breaking glass sound means there's something wrong with your Mac's hardware, usually related to memory. Remove any third-party RAM if you haven't already. If you only have memory that was installed at the factory, try swapping it with other RAM.
"Musical" beeps
- Do you hear four or eight beeps? If you heard eight, skip to Solution B.
- Shut down the computer.
- Start from a system software CD or DVD (insert the disc, restart, and hold the C key during start up). If you don't hear any beeps now, continue to Solution A. If you still do, skip to Solution B.
Tip: If you can't start from the disc using the C key, try using Startup Manager.
Solution A
Restart the computer from its hard disk, but press and hold the Shift key during startup until you see a "Safe Boot" (Mac OS X) or "Extensions off" (Mac OS 9 and earlier) message.
Mac OS X: If the computer starts up (Safe Boot) and you don't hear any beeps, you'll need to
troubleshoot other startup issues.
Mac OS 9 or earlier: If the computer starts up with extensions off and you don't hear any beeps, an
extension conflict is the likely cause. If you still hear the beeps with the extensions off,
perform a clean installation.
Solution B
Remove all third-party memory (RAM) that wasn't installed by the factory. If you only have memory that was installed at the factory, try swapping it with other RAM. If you have installed additional memory, remove it.
If you can isolate the issue to a particular memory card, replace it. If necessary, take your computer to an Apple Authorized Service Provider for additional diagnostic tests to determine the exact cause of the issue. There may be a fee for this service.