booting Luck of the draw if my PC boots

[iVapeNow132]

I've had my PC for a about 4 years with Windows 7 running off a 120GB Corsair LS SSD. For quite a while now, 7/10 times my PC will fail to fully boot first time prompting me to launch start up repair... which does nothing to help. The system usually crashes either in the pre-windows environment or as the screen to log onto a user account appears. I've done some digging on-line and found that some users are suggesting either malware that is affecting the pre-windows environment, too many applications launching at start up (I don't get why that would cause my system to crash even before logging in) or my SSD is nearing the end of its life (I don't get any crashes when my system has managed to fully boot unless it's a DX11 error which is still rare for me)...and 40GB are still free on the drive. Could someone help narrow this down to the most likely cause and possibly suggest a fix? It's bugging the hell out of me. 

 

I'm happy to give more info if needed.