OS or HDD problem?

[Governor]

So I have been having some very slow boot up times. This started to happen just yesterday. I usually get stuck at the Welcome screen for about 3-5 minutes and when I do get past that I have a black screen for 1 to 2 minutes. I built my own PC about 2 months ago and had no problems until now. I have a WD Blue 500gb 7200rpm hard drive and have no clue what to do or what's going on. Just before I turned my PC on the first time before this happened I was checking why one of my fans didn't work while my PC was on. Should I have not of done that? Do I have to buy a new HDD? Help?

[perplex]

first think i would do is back up whats ever on your hard drive, to something else

then i would do it run "HD Tune" and do a full error scan, might take 30 mins to 1 hour or longer, and if any red come up, then its the drive

report back after you have done that

make sure to back up what ever is important first

[andes21]

Just as perplex said back up before anything else and you might want to check if there was any update to your drivers and you might have a bad case of drivers bugs crawling in your system

[Governor]

Okay will do but some new problems has occurred. The User account control. If I select yes the gray lighting effect stays and freezes the screen but the audio keeps working. If I press CTRL ALT DEL to go to the task manager it makes my computer slow x10 and everything becomes unresponsive. Pretty much every site I load takes minutes to load to not at all and every application I use it some times pops up as High disk usage from Norton. I have not been able to play most of my games and not been able to install updates for them or download things.

UPDATE: when i do get to access my task manager and i go into performance this is what it shows http://gyazo.com/b4c8e4d21bd7c5b4c3746fba477d3dbb

I'm pretty sure 0% CPU usage isn't supposed to be there. And when it's not 0 its 1-9 and sometimes 10 or 12%.