I have been using this laptop for almost two years now. Its an Intel 2nd Gen i3 with 4 GB of RAM with a 512 MB of ATI Radeon 5470 GPU running the 64-bit version of Windows 7 ultimate (Not too impressive I know). But anyhow, provided my limited gaming and programming needs, the configuration has sufficed my demands quite well.
I have this habit of leaving my computer on sleep (quite a lot, that sometimes it sees a restart after a month, or more). Last week there was a Windows Update installed on my computer which demanded a restart. So I did. The system took a lot of time restarting, say something like 20-25 minutes or so. I thought maybe its because of the time since it had been restarted that its taking such a long time to reboot. But after it had completely rebooted, I realized that it was actually working quite slow. For example, with even just 2-3 tabs open on Firefox/Chrome (I tested the scenario on both) there was quite a lot of hanging here and there, and the "Not Responding" sign flashing every now and then on the title bar. So I decided to reboot it once more (considering it the simplest of the options available). But yet, it behaved the same way, same half-an-hour of reboot time and all.
As of now, I've run a complete system virus scan, tried to check it with the windows troubleshooter, have scanned the Device Manager for any hardware changes considering there might be hardware corruptions but none of these has resulted in any satisfactory solution. The system doesn't crash either. It just runs damn slow and I have no clue of why so. So please suggest an exhaustive approach of how I should troubleshoot the system so that I can finally be, at least, satisfied even if I need to reinstall the OS. Also, please suggest any BIOS related troubleshooting methods that are worth consideration.
As suggested by Darth Android, I'm including the S.M.A.R.T. analysis result from CrystalDiskInfo so that it gives a better insight of the current scenario my laptop is in:
The last item in the itinerary that's not in this screenshot is Free Fall Protection which has a Current and Worst count of 200 and 0 Raw Values.