mac issues: grey screen,. cannot reinstall mac os from recover, unapproved caller

Well the past few days have been a near disaster. I recall this whole problem starting when I was using chrome and suddenly I couldn't access pages and safari wasn't working either. I was getting the oh snap page from chrome. So I exited out and then tried to reopen chrome and the bottom icon of chrome would just bounce once (usually it bounces until it opens) and would never open. Then I tried to restart the computer but none of the restart or shut down buttons ere working beneath the apple logo. So I held down the power button and to force shut down. Upon trying to turn the MacBook back on I am stuck in the grey screen forever. I have tried everything on the apple troubleshoot pages. I tried safemode and I was stuck in the grey screen still. I tried the safe mode where it shows you the progress and for some reason I could get back in but then the cycle began anew of the chrome not working... I tried the PRAM reset or whatever it's called. So I finally tried to do a MAC OSX from the recovery and sometimes it won't let me start the reinstall and other times it gets to like 6 minutes remaining and then it will all of a sudden stop.

This is a really terrible time for my computer to stop working because I have finals and papers due very soon. To make matters worse I made an appointment with the genius bar today and unfortunately I was less than 20 minutes late to my appointment and they said I'd have to come back tommorrow! So basically I have lost many hours in the past 2 days. If you could help me I think I'd owe you a life debt.

Edit: I forgot to mention that I did all the verify disk and permissions and repairs in the disk utility in the recovery. I also ran the apple hardware test and it said nothing was wrong. At times when the computer was able to boot but having the troubles I was getting the unapproved caller message