Three performance problems in Windows 7

Hi! I've been using Windows 7 since 2010 and I got this problem/s:

Problem 1:
Windows detected a Hard Disk Failure
Windows tells me to back up my files and contact the manufacturer of my PC. Yet, I notice no symptoms at all. So, I just chose to stop Windows alerting me for that problem.

Problem 2:
I always used Readyboost to speed up my PC. But, after some months from the alerts above, I cannot use Readyboost. In the ReadyBoost tab under Properties, it says that
" ReadyBoost is not enabled because the service responsible for ReadyBoost (Sysmain) has been turned off on this computer. An administrator can turn the Sysmain service back on."
I tried to search the web for that and I found out that the service has the name Superfetch in services.msc. It is stopped. I tried to manually turn it on but it displays the error "Windows could not start the Superfetch service on Local Computer. Error 2: The system cannot find the file specified. I was wondering if this is the cause of the Hard Disk failure...

Problem 3:
After some time, I noticed that my RAM usage is quite high. It is usually above 40% (I have 2 GB RAM), and it sometimes peak to 70 or 80%. To resolve it, I run Smart RAM in Advanced SystemCare to push it down. And, it returns to 20-30%. But, after about 15 mins. it returns to 40% or above. I have to use Smart RAM again...

I have been searching different websites for those three problems and I can't find a solution. Below are some of my Task Manager screenshots. Thanks in advance!