Boot stucked on a white screen & gray apple

Hello,

I am using an Imac purchased in 2010, operrating a Maverick OSX system.

Since 2 days, my Imac does not boot and gets stucked on the white screen with a grey appel, and a small grey square sticked to the mouse cursor.

I tryied all tips & tricks suggested by several osx websites (after having disconnected peripherals), I mean:

- reset nvram

- start in safe mode, I checked the hard drive with the disck utility and corrected several permissions; but the reboot gets fixed at the same level

- fsck

- resinstallation of a time machine system backup

- installation of a new version of osx

Noone of those operation helped.

Thinking it was an hardware element which had an impact of the OSX operations, I tryied to boot on the my Windows 7 via Bootcamp, and the Windows OS worked properly on my Imac ! 😮

So I really don't know what to do next; do you have an idea ?

Thanks in advance for your help .

Nicolas