I have a late 2007 7,1 iMac with Mavericks on it that is having issues. It will not come out of sleep mode and when rebooted hangs on the apple logo when booting up with no spinning wheel thing (not the beach ball, the other thing). In February 8 months ago, I replaced the stock hard drive for space purposes and to hopefully speed up the computer. I put in a Seagate 2TB hybrid drive that I got from OWC and it has sped up the computer a bunch. About last week the mouse pointer started to move a little slower across the screen like it was hanging a little. As of yesterday I started having the no wake up from sleep and the other problem, hanging on the apple logo. I got on the phone with the OWC people and they had me hold the option key and select the "Recovery 10.9.4" icon and then check disk utility. There I have it check permissions and I find about 25 or so items and then I repair them (the OWC lady said this was normal). I then have it verify the disk and it states that the disk "appears to be OK" so there is nothing to repair. I can then restart the computer and it works fine. I have ONYX on my system and had it check everything and it repaired some more permissions and also said everything was OK but if I let it sleep the problems come back. How do I know if this is my HD failing or a software issue? What should I do?