Hi guys, before I address my issue thoroughly I'd like to put my iMac specs out there. It's a mid 2007 iMac 24" that I bought from eBay a year ago,love the machine, great for my graphic design work. Now the issue came along about 3 weeks ago, the flashing folder with the question mark popped up when I booted up, so sometimes it would be a successive boot and sometimes not. I tried many things such as Onyx app, repairing the disk via disk utility, etc and nothing worked. It came to a point where my Mac would freeze, so I thought it would be a hardware problem? But my SMART status is verified? I've done the PRAM and what not. Now on to present day, I've wiped out whole OS(ML) and installed Mountain Lion again and nothings really happened, the boot ups been successive until I upgraded to Maverick, the flashing folder with a question mark came once. Do you think it's a hardware fault? Shall I replace the HDD? Thanks!