What else could it be!?
I have suddenly become clueless as to this problem. I own a mid 09 Macbook Pro which has developed the flashing question mark syndrome on startup. I did my research and was told that the issue was probably the HDD cable since the computer's upgraded solid state hard drive could be plugged into a different Mac and still work. However when I installed the new HDD cable the problem still persisted. I tried all of the hotkey fixes such as starting in safe mode, selecting the startup disc, etc... The only thing I have not yet done is reinstall the operating system, which I can't do because I don't have the disc. Is this a common problem or did I just have a million dollar baby?