Geez, your computer is calm and yet so slow. It's prepping for a storm, I mean, a hdd or other hardware failure. But in order to be sure keep it powered on and in windows mode for at least 4hrs. According to you it is hardly used and I assume that it is also hardly powered on and into windows mode. So the services that are scheduled to run might have been piling up like 10 guys stuck wanting to go out as soon as you open the door. And some of them use the internet so when you disconnected it from the internet, they just shut up. The antivirus and defragmenter also runs on schedule. Automatic upkeep of windows 7 also runs on schedule. Just go buy SSD and make it your system disc then make you 1T hdd as databank. Uninstall any browser toolbar that has RSS Feeds.
I hope these helps.
The Turbo Button is only available in PCs made before the 90's. Instant cpu overclocking.
No, the computer is being used everyday for business, it is not being used as gaming, nor serve a lot on the web. We have Norton 360 all along and I never suspect it's been infected. Up till it failed, it was working perfect. No body else touch the computer for a month other than my wife using for business.
I tried to recover the computer, it does not even work. I managed to upgrade to Win7 Pro, but the problem remains.
You could try (temporarily) disabling Norton and other AVs you might have, (while disconnected from the net).
It can happen that AV's get into a knot trying to solve something,especially if you have more than one of them running.
That's just a long shot suggestion, if that was happening you would probably see heavy disk use, and you say the disk use is quite low.
Another long shot, could be failing memory chips; if you have compatible memory on another machine you could try swapping them.