inconsistant boot trouble, please help

[bluemac]

Hello - I am new

Blueberry imac G3 panther osx 10.3.5 (3gb of 10 avail.)

I am having strange inconsistant start up problems that have never occurred before in 5 years used. upgraded memory to 512 MB 2 years ago no problems.

This is one of 3 errors I receive upon boot up, screen goes black and in the top left corner is the following error:
disc os5:I/O error single user shell terminated, restarting.

The other error I started receiving resembles the os 9 start up folder flashing a question mark inside the folder.

I also hear strange noises that resemble a ping pong ball dropping and when I hear that noise it always freezes.

Any help???

[giskard22]

I am very worried about your internal hard drive. First of all, turn off the computer and stop using it. Second, you need to back up your data. You need a way to do this, if at all possible, without booting from your internal hard drive again. If you don't have a choice, boot up and try burning a CD or copying things to a USB thumb drive or whatever.

Once you've done that, you can boot up from the OS X installer disk and use Disk Utility to check your drive. However, Disk Utility can't usually diagnose physical failures, and that's often what causes unusual noises. What's likely happening is that your hard drive is seizing or having some other mechanical failure that sometimes is preventing it from spinning up.

I would look into getting a new hard drive ASAP. It's not that hard to replace the drive in that iMac, but if it has Firewire you might just get an external and run off that full time. I assume you're not going to try to keep this computer for years and years, and an external could be used with a replacement.