Q: I Mac progress bar starts and go halfway but do not complete. How to solve the problem and start the Mac?

Try starting holding shift key at bootup, if that does the same thing then...

Tough without the Install Disk which would be preferable, but try fsck...

To use fsck:

1. Start up your computer in single-user mode to reach the command line. Hold CMD+s keys down at bootup.

Note: If necessary, perform a forced restart as described in the Emergency Troubleshooting Handbook that came with your computer. On desktop computers, you can do this by pressing the reset/interrupt button (if there is one) or holding down the power button for several seconds. On portable computers, simultaneously press the Command-Control-power keys. If your portable computer doesn't restart with this method, you may need to reset the Power Manager.

2. At the command-line prompt, type /sbin/fsck -fy

(SPACE between fsck AND -fy important)

3. Press Return. fsck will go through five "phases" and then return information about your disk's use and fragmentation. Once it finishes, it'll display this message if no issue is found:

The volume (name_of_volume) appears to be OK

If fsck found issues and has altered, repaired, or fixed anything, it will display this message:

***** FILE SYSTEM WAS MODIFIED *****

Important: If this message appears, repeat the fsck command you typed in step 2 until fsck tells you that your volume appears to be OK (first-pass repairs may uncover additional issues, so this is a normal thing to do).

4. When fsck reports that your volume is OK, type reboot at the prompt and then press Return.

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