iMac only reboots in Safe Mode.

Reinstall OS X 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.

Continue working in Safe Mode, then. A reinstall may not succeed meaning you would need to do an Erase and Install. Therefore, you may prefer to wait until you aren't so pressed for time.

Your profile shows that you're running OS X 10.6.8. Is that accurate?

Your profile shows nothing. Is that accurate?

I haven't used 10.6 in a long time, so some of the details in these instructions may be a little off.

If you have more than one user account, the instructions must be carried out as an administrator.

Launch the Console application in either of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

Step 1

Select the system log from the SYSTEM LOG QUERIES menu on the left. If you don't see that menu, select

View ▹ Show Log List

from the menu bar.

Enter "BOOT_TIME" (without the quotes) in the search box. Note the timestamps of those log messages, which refer to the times when the system was booted. Now clear the search box and scroll back in the log to the last boot time when you had the problem. Select the messages logged after the boot, during the time something abnormal was happening. Copy them to the Clipboard by pressing the key combination command-C. Paste into a reply to this message (command-V).

Please include the BOOT_TIME message at the beginning of the log extract.

If there are runs of repeated messages, post only one example of each. Don’t post many repetitions of the same message.

Please do not indiscriminately dump thousands of lines from the log into this discussion.

Important: Some private information, such as your name, may appear in the log. Anonymize before posting.

Step 2

Still in Console, look under System Diagnostic Reports for crash or panic logs, and post the entire contents of the most recent one, if any. In the interest of privacy, I suggest you edit out the “Anonymous UUID,” a long string of letters, numbers, and dashes in the header of the report, if present (it may not be.)