I cant run a scan on normal mode?

I have recently been having problems with my laptop. The only thing that barely works on normal mode is my games. Everything else including internet and anti virus freezes up and doesnt respond. You can actually wait on the internet and some other apps but it takes like 5 minutes for it to respond. When the anti virus freezes up in never responds. I have already ran a few full scans on safe mode and I am pretty cleaned up. But dont i need to scan it on normal mode now that i still have issues? The only other problems i can think of are getting notified sometimes on reboot that by batteries storage cap is very low. Also on reboot i ran system diagnostics and each one mentioned "replace hard disk 1" as my hard disk check obviously failed. Do either one of these effect my normal mode performance? Everything runs perfectly fine in safe mode. So what do i do and where can i start from here?