I keep a copy of Snow Leopard install DVD on a flash drive just in case of problems, Have you tried force booting from the original install disc that came with your iMac.
There seems to be many problems arising with Lion...Personally I'm staying with Snow Leopard until things get ironed out by Apple.
Try loading the original install disc and directly after you hear the startup chime press the C key = Boot from CD or DVD
Try these other options also -
Command+V = Starts your system in Verbose mode. (lists what is loading during startup, as opposed to the spinning icon with grey screen)
Command+S = Single user mode (used for troubleshooting in most cases)
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Also once you get it up and running check for firmware updates that are available for your model
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Command+Option+P+R Zaps Parameter RAM (Note: Make sure to push this key combination directly after the startup chime, and hold the keys until you hear the startup chime again.)
If you're able to get a normal boot and Lion loaded with a normal screen I would suggest putting a install on an external hard drive for future emergencies.
I keep a copy of Snow Leopard install DVD on a flash drive just in case of problems, Have you tried force booting from the original install disc that came with your iMac.
There seems to be many problems arising with Lion...Personally I'm staying with Snow Leopard until things get ironed out by Apple.
Try loading the original install disc and directly after you hear the startup chime press the C key = Boot from CD or DVD
Try these other options also -
Command+V = Starts your system in Verbose mode. (lists what is loading during startup, as opposed to the spinning icon with grey screen)
Command+S = Single user mode (used for troubleshooting in most cases)
Command+Option+P+R Zaps Parameter RAM (Note: Make sure to push this key combination directly after the startup chime, and hold the keys until you hear the startup chime again.)
If you're able to get a normal boot and Lion loaded with a normal screen I would suggest putting a install on an external hard drive for future emergencies.