macbook pro wont start unless I restore from backup (only a temporary fix)

Hi,

I have a mid 2009 Macbook pro (2.26GHz Intel Core 2 Duo processor, 8GB Ram, moutain lion) that randomly freezes when i try to log in after sleeping. When I log in, the pin wheel shows up and my computer doesn't go beyond log in. I manually turn off the computer and after turning my computer on it leads to a grey screen (apple sign and spinning wheel). At this point the computer stays at a grey screen without ever getting to the log in screen.

The only fix I found is to restore from my latest backup (in Recovery Mode) but this only solves the problem for about a month . After about a month I run into the same problem outlined above.

I need help identifying the underlying problem. Is it a hardware or software problem?

I ocassionally hear a clicking noise from what I assume is my harddrive (HHD). Disk Utility sometimes helps get beyond the log in screen but the computer quickly freezes after I get to the desktop.