last week my iMac started booting to a white screen...I reset the PRAM and booted the iMac with the installation disk and did the 'repair disk'...this worked, but now I'm back to a white screen and now when I boot with the install disk, my HHD doesn't show as an option in the side bar under the disk utilities or when I finally get the HDD to show (after rebooting numerous times) all the options to 'repair disk' or 'repair permissions' are grayed out. For 3 days I haven't been able to select the HHD or get the iMac to boot. I believe I have a bad HHD, but before I buy a new one and replace the HDD, I would like to know for sure that there's not another issue other than a bad HDD, like the logic board. Does it sound like from the above, a bad HHD? There's NO Apple service centers near me, so I can carry the iMac to Best Buy and let the Geek Squad take a look at it...or just take a chance and buy a new HDD and replace it myself... Any suggestions would be helpful.