Heavy lagging issue.

I am lagging as I write this thread.
My computer was fine 2 days ago.

I had an unusual slow startup since yesterday and when I am in my desktop screen. I was lagging every 3 - 5 seconds. Low CPU load, low physical memory usage. But I was lagging so badly that I have to wait so long.

I've scanned my computer using Avast! and Malwarebytes' but both returned with no viruses/malwares. Therefore, I need some help from people in this forum.
P.S ; My ATI Catalyst Control Center would sometimes disappear from my taskbar.

& When I'm loading my startup, sometimes I can't finish loading everything in my taskbar. It would stuck at there sometimes without the usual programs. I've tried diskcheck too, but it stucked at "Windows will now check the disk." and I waited for 1 whole day with no progress at all.

How do I use it?

My absolute maximum latency is 883. What does that mean?

They are all green.

But I don't know why is it lagging so badly. Help would be appreciated.

Would a clean install help?

I did not see that you had scanned your system in SAFE MODE...

You NEED to scan in SAFE MODE when you suspect you have been infected. If you do not, then you will not find them. Viruses these days are build with stealth technology that loads when the system starts.

When your system completes the BIOS loading, start tapping the F8 key every second or so... you will get the white text screen with the top selection being SAFE MODE. IF you need to update AV signatures, use SAFE MODE w/ NETWORKING.

Or did you scan in SAFE MODE?

The other thing is that your HD could be in trouble. Make sure you perform a couple of controlled shut downs, and a CHKDSK /F (if your system is backed up that is) and see what happens then.

Let us know...