BLUE SCREEN on start up...intel 24inch imac

My mac 24inch intel has a blue screen at start up. Running osx10.5.8.

I have started in safe mode but Im not sure what to do once its in safe mode. And I have started with the Command-Option-P-R keys, where it eventually goes to login. However I didn't have a log with this computer. When I try to log in it thinks about it for a minute then goes back to login screen. Do you have ideas as to what i can do?
thanks
Edit/Delete Message

So what you're saying, if I'm understanding you, is that you CAN log in via safe mode? Is that right?

If so, that's good! It means your data is probably fine and almost everything is working. The problem is that something in your startup routine (in non-safe mode, so some third-party item most likely) has gone wrong.

The first thing I'd recommend doing is booting into Safe Mode and making a backup if you haven't done that lately. Second thing I'd do is run Disk Utility in Safe Mode, that may just fix the issue (have you been running any kind of maintenance? Macs don't need much but they do need a little!).

Let us know if that fixes things. We'll have other suggestions if it doesn't.

I'd also say that perhaps this is a "sign" that it's time for you to upgrade that machine to Snow Leopard or later. While you still can, I mean (they won't be making SL discs available forever, and you have to get to at least Snow Leopard in order to move to Lion).

BLUE screen

I have tried to start up in safe mode but last night it was just running forever so I switched it off and restarted. Now it goes to the login screen but i cant login. It wont accept the password. Any more suggestions?

I don't know whether you were successful in entering Safe Mode from your first post? If you were, Safe Mode automatically verifies the hard drive before you get the desktop. If you were not successful in entering Safe Mode:

Boot the machine with your Leopard DVD and run Disk Utility from the DVD. Do a verify and repair and also repair permissions. Let us know the result.

Blue screen

Is there anything you can do to get the startup disc to show up?

I have inserted the startup disc and nothing happens, imac is stuck on the login screen. Is there anyway to start it up in another mode or something? Thanks

HOw do I run Disk Utility in Safe Mode

exposurenz said:

HOw do I run Disk Utility in Safe Mode

Click to expand...

You don't. As already mentioned, Safe Mode by itself runs an automatic verify on the hard drive. However, if you can't get in Safe Mode you have other problems.

If you are inserting Leopard DVD, rebooting sand holding down 'C" immediate;y after the chine the machine should loot from the DVD and leave Installer and go to Utilities > Disk Utility > Repair Disk. If this is not working major problems alas.