Why is My Login Screen Not Loading

First try starting up in Safe mode by booting with the Shift key held down. Next, insert your system installation disk, boot up holding the "C" key down and run disk utilities (repair) from third page pull down menu. Next we'll try resetting the System management Unit but let's see if these things work first. Since you don't get a screen with a question mark folder, the hard drive is probably all right. We just need to slap the system around a little bit to wake her up and get her to act right ;-)