After I finish my work on the Mac for the day, I put the Mac to sleep [option > command > eject]. When I need to resume, I hit any key on the keyboard and the Mac starts readily.
Recently, I was out of town for 4 days and had left behing me a sleeping Mac. Upon returning, I found that the Mac would not wake up with a tap of the key. It had shut down and I had to switch it on using the power button. When I, after working with on the Mac for sometime, put it to sleep, some strange thing happened: the Mac started giving out an alarm: 3 beeps followed by a pause. the alarm would not stop and the Mac would not start despite me hitting several keys several times. I could silence the alarm by only by shutting out its power supply. I then pressed the power button again to start the Mac. After working on the mac, I put the Mac to sleep in the regular manner. After 2 hours later, I was woken up from my sleep by the alarm given off by the Mac. I could silence the Mac by keeping the power button pressed and shutting down the Mac. This morning, when I started the Mac, a grey 'reading bar' appeared beneath the Apple logo and after a while I had to enter my password to access the Mac.
I had a 'grey line experience' earlier too and I did this: went to disk utility and verified the internal drive which was given a clean chit. I then did a repair of permissions. I am yet working on the Mac and have not put it to sleep.
In between the first and second 'breakdown' [I do not know how else to describe what had transpired] I had done this: download 2 apps...paintbrush and seashore.
Any instructions and guidance regarding what the problem is and what I should do will be deeply appreciated.