iMac stucks in grey screen after the Apple logo goes off

[56lian]

I'm from China and My English is bad,so reply me if you don't know what I'm saying
Yesterday when I'm watching some videos on my mid-2011 iMac it suddenly went black screen with no sounds. I waited for like 5 minutes and nothing changed.
I pressed power button to let it reboot,and a grey screen appears after the apple logo and the spinning circle.
Tried to do everything like safe mode,reset PRAM SMC,boot up from install disk,boot up from Recovery disk,etc.
I can get into singleuser mode and repair disk,but nothing happens.
I remember iMac mid-2011 has some graphic card issues and hard disk issues so I was wondering is it hardware problem or software problem.
Anybody have same issue with mid-2011 iMac?
Or also stuck in grey screen after the logo?
Do you guys have any solution?Please tell me!

 

[Dolfke]

try to use the recovery partition, or to startup from another attached disk, and go to disk utility and check repair disk.

 

[56lian]

try to use the recovery partition, or to startup from another attached disk, and go to disk utility and check repair disk.

All these are useless,but when I go to apple store they tells me it's a graphic card problem and they are gonna fix it for free.

 

[yjchua95]

I'm from China and My English is bad,so reply me if you don't know what I'm saying
Yesterday when I'm watching some videos on my mid-2011 iMac it suddenly went black screen with no sounds. I waited for like 5 minutes and nothing changed.
I pressed power button to let it reboot,and a grey screen appears after the apple logo and the spinning circle.
Tried to do everything like safe mode,reset PRAM SMC,boot up from install disk,boot up from Recovery disk,etc.
I can get into singleuser mode and repair disk,but nothing happens.
I remember iMac mid-2011 has some graphic card issues and hard disk issues so I was wondering is it hardware problem or software problem.
Anybody have same issue with mid-2011 iMac?
Or also stuck in grey screen after the logo?
Do you guys have any solution?Please tell me!

If it's a 27" with the Radeon 6970M card, Radeongate hit your Mac.

It's covered under an extended repair program by Apple, so you can have the card replaced without cost.