Why can't I login in on my computer?

I do not to much about macs.. Have you tried starting it up in safe mode?

If you have another computer on your network, you could try telnet‘ing to your Mac. If you’re somehow typing your password wrong, you’d at least get back a message stating that “login failed.”

If you are able to logon successfully via telnet, then it would sound like the problem isn’t with authentication, but something else in your desktop session startup.

Try the telnet, and then let us know how it goes.

[update]:

Actually, ssh is what you really want to use, instead of telnet. Looking around, it appears that the Mac might need some command-line config to enable telnet… and of course, you can’t do that right now.

PuTTY is a free, universally used ssh client for Windows, if you need it. If you have another Mac, then go into the Terminal and simply type: ssh YOUR_BROKEN_MAC’S_NAME.

Try the following, nicked from Here

Clear the PRAM Reboot your computer while holding down the command-option-p-r keys simultaneously. Don’t let up until you have heard the startup chime three or four times.

Reset Open Firmware. This is a step for G3, G4, and G5 Macs only. If you have an Intel Mac, you should Zap the PRAM (see previous point).
Reboot your computer while holding down the command-option-o-f keys simultaneously. At the prompt, type
reset-nvram and hit the Return key, then type
reset-all and hit the Return key again. Your computer will reboot.

* Note that these commands are correct for New World machines, those with colored plastics (iMacs, Blue and White PowerMac G3) and newer. Old World machines (G3/233 All-in-one, beige G3, etc.) are slightly different—just type the reset-all command.

File System Check. This can be done in several ways, including
1. Boot to single user mode by holding down command-s during the boot process, then at the prompt typing
fsck -y and hitting the Return key. Continue to run fsck -y until no errors are found. (Note: if your hard drive is journalled, you will need to run fsck -yf. Attempting to run fsck -y will result in a message reminding you of this. Thanks to Petroffski.) Then type
shutdown -r now and hit the Return key to reboot.
2. Boot to a full OS X Install CD. From the Installer menu, select Disk Utility. Select your hard drive boot partition whose file system you wish to check, click on the First Aid tab, and click the “Repair Disk” button.
3. Boot to a third party disk utility CD and run the file system check offered therein. At this time, I can recommend DiskWarrior http://alsoft.com and Drive 10 or Tech Tool Pro 4 http://micromat.com . The third party disk utilities generally do a better and more complete job than the first two options and have been known to rescue drives that are inaccessible.

Reset PMU. Software PMU reset is ONLY for Apple portables, not desktop computers. The procedure is specific to each machine, so I can’t give a synopsis here. Instead, check Apple’s Knowledgebase article for resetting PMU on iBooks and PowerBooks and Apple’s Knowledgebase article for resetting PMU on MacBooks and MacBook Pros. This does roughly the same thing that pressing the PMU button or CUDA switch does for desktop Macs.

If you’re struggling to boot from your OS X CD/DVD, try holding alt (option key) at startup with the CD/DVD in the tray, and see if you can select it as the boot volume from there.

keep us posted!

aside: I wonder how yannick manages to post to fluther without logging in… hmmmm ; )

Hey all, thanks for all the tips. @benseven, I’m actually using a public computer which I have limited access to – hence the delayed posts – but i will print off all your suggestions and try them out when I am back home where my iBook is. I tried to safe boot last night but exactly the same thing happened at the logon window (except it said, ‘safe boot’ of course).

As for the ssh suggestions, I don’t think I’ll be able to make use of them because my computer is not on the network with any other computers…But thanks anyway to all of you, and I’ll let you know how I went as soon as I get a chance to.

The final option, if it looks like you’re going to really struggle to get this baby working again, is as follows:

For this recipe, you need:
• A firewire cable (6pin-6pin, looks like a USB cable but one edge is more pointed)
• Another Mac, but only if this isn’t an Intel machine – it has to be G3 / G4 / G5.
- Also make sure this machine is backed up, better safe than sorry
• An external HD or some other way of backing up your vital data
• An OS X Install CD or DVD that’s for PowerPC (i.e not an Intel Mac).

Summary:
We’re going to recover any vital data from your machine to the other mac, back it up onto an extrenal HD or DVDs/CDs, then use the other mac to re-install your iBook.

Steps:
1. Start with the ‘Other’ mac on, and the ibook powered off.

2. Connect the Firewire cable to the FW ports on both machines (again, looks kinda like USB)

3. Power on the iBook holding the ‘T’ key down. This step makes your iBook boot into ‘Target Firewire Disk Mode’ – making it appear like an external drive on the desktop of the Other mac.

4. Back up all your data, which is stored in your home folder under ‘Users’ – back up the whole home folder, and also back up ‘Preferences’ under iBook Harddrive > Library > Preferences

5. Once you have backups, back-up again to an external HD or CDs / DVDs : )

6. Insert Install CD/DVD in ‘Other Mac’

7. Run the Installer – this will require a restart of the ‘Other Mac’, but the iBook will still show up in the installer as an external drive, so don’t do anything to it for now – leave it on.

8. Go through the various prompts required until you reach ‘Select Destination’ (or whatever – the hard disk screen). Make sure you select the iBook’s Hard disk to install on, or you will wipe the Other Mac! The iBook’s HD should have an orange external FW drive icon.

9. Continue through the installation process. Make sure you choose ‘Erase and Install’ from the ‘Customize’ option so it wipes the disk and you really are starting afresh.

Once finished, the ‘Other Mac’ will reboot, and load up (usually) the newly installed OS over Firewire. You’re using the ‘Other Mac’ as a ‘screen’ as such, for the iBook at this point. You can just go ‘Shut Down’ and the Other Mac will switch off. Now power off the ibook using its power button.

10. Switch it back on. If Steve Jobs is smiling upon you, it should boot into your freshly installed Mac OS X. If not, try holding ‘Alt’ (or rather, the ‘option’ key) as you power on, and select the OS X installation there.

Continuing our chat from the other question, haha, your iBook specs will be fine! Best of luck!

Well, I’m glad to say this is posted from my newly updated iBook, now running Leopard :D I’m about to update to 10.5.2, and I’m a tad nervous, but hopefully all will be well!

Ok. Yet another update., if anyone is actually still following this question… Am now on 10.5.2, very pleased. However, my next worry is the ‘Leopard Graphics Update’. I have read a couple of very negative things about it in relation to powerbooks, and am wondering whether I should brave this update on my iBook or not…

Good work!
Glad that worked out for you… I doubt the graphics update will kill it – it should be OK.