Currently Being ModeratedJun 23, 2013 5:49 PM (in response to tt0222)
If it only shows the folder with the questionmark at startup time, that means that it can't locate the drive with the OS on it. Often, this indicates that the drive is having some serious errors, but it it possible that it is only a few corrupt files. Running the Disk Utility form the Recovery partition or Internet Recovery should help you to tell how severe the issue really is. You may need to replace the HDD to resolve this.