IMac first shows progress bar on startup and then won't start up at all!

Question

Hi,
My iMac's somewhat ill I'm afraid. When I power it up, the Apple gong goes and I see the grey Apple logo appear. Few seconds later an progress bar shows up and it doesn't fill, in a minute it'll just disappears and the spinning thing under the logo appears. I've been waiting for over an hour and still nothing happened. I've tried force-powering it off and boot it up again, but still the same results, this is very very very annoying, especially since I don't know what to do at all about this expect for a complete clean install, but that'll be the last option I want, because all my photo's are on it, etc.
I've installed, an complete clean install, of Snow Leopard a month or two ago, and yesterday I powered the computer off the regular way.
Thanks a lot in advance you guys!
EDIT
Another weird thing going on: I have my hard drive configured in two partition, one for Windows (sorry, needed to run AutoCad) and one for Mac OS. Now when I start up with the option button I get to see the two partitions and their names. My Mac drive now has got a different name, it's the same name, but with a " 1" behind it.
When I select the partition on Windows Vista, it now shows these disturbing folders:
http://i49.tinypic.com/2rxjpd3.jpg
Message was edited by: RobinZ.

Answer 1

HI and Welcome to Apple Discussions...
Boot from your install disc and run Disk Utiity to see if there are errors on the startup disk that need repairing.
Insert your install disk and Restart, holding down the "C" key until grey Apple appears.
Go to Installer menu and launch Disk Utility.
Select your HDD (manufacturer ID) in the left panel.
Select First Aid in the Main panel.
*(Check S.M.A.R.T Status of HDD at the bottom of right panel. It should say: Verified)*
Click Repair Disk on the bottom right.
If DU reports disk does not need repairs quit DU and restart.
If DU reports errors Repair again and again until DU reports disk is repaired.
When you are finished with DU, from the Menu Bar, select Utilities/Startup Manager.
Select your start up disk and click Restart
While you have the Disk Utility window open, look at the bottom of the window. Where you see Capacity and Available. *Make sure there is always 10% to 15% free disk space*
If you cannot boot from your install disc, try booting in Safe Mode
What is Safe Mode
*" because all my photo's are on it, etc."*
If you can get the iMac to boot normally I suggest you back up those photos and any other important data to an external source ASAP in case there's a problem.
No idea why you are seeing those folders in Windows. Boot from your install disc and see what's going on.
Carolyn