It all started when I woke up the iMac (the one in my sig for specs) from sleep and all I got was the blue login screen background, no white dialogue box for logging in or anything. So, after waiting for it to sort itself out, I tried a variety of keyboard commands, but still had to turn it off at the back. Now when ever I boot up from off, the light on the chin illuminates solidly, and the screen remains off (the HD whirrs into action also). It takes about 10-15 seconds for the 'hummm' sound to happen before booting as normal. Before this the iMac would be at the login screen in about 10 seconds from pressing the on button. I also get a fair bit of beachball and some freezes in safari now on. It was all going so perfectly before... Anyone know what may have happened/how to get it back to normal? Or will it have to be reinstall of OS X ...? Thanks for any help!