Apple iMac "Core 2 Duo" 2.4 20-Inch (Early 2008) Specs
Identifiers: Early 2008 - MB323LL/A - iMac8,1 - A1224 - 2210
I'll change the iMac icon to the correct one. Hook it up to an external monitor and see if you get the desktop. It sounds like it may be hanging on boot up. Try holding down the Shift key on startup to try starting in Safe Mode. Try what remac said, select the drive on the left and run the repair in Disk Utilities till it runs clear.