Experience Index score for Hard Disk went down??

So I bought this gaming PC a little while ago.

Win7 Home Premium 64bit
Phenom II X4 3.2GHz
Radeon 5870
4GB DDR3
500GB SATA

All was well until two weeks ago where EVERYTHING started slowing down. I suspected it might be the hard disk's transfer bandwidth so I ran the Assesment for the Windows Experience Index... indeed it used to be at 7.3 now it went all the way down to 5.3. This is really weird because my hard disk is almost empty (I only use it for gaming every once in a while). I ran CCleaner, Windows' Disk Cleaner, defragmented, ran the usual scans for malware (Malwarebytes, SUPERantispyware, spybot and so on) without results, disabled a lot of services and uninstalled some crap but it's still slow (opening Firefox takes up to 15 seconds sometimes when it used to be instantly)

Thankfully it doesn't affect my gaming but it's still a pain in the neck whenever I'm just browsing the Net or doing something else. Any idea guys?

 

I'd suspect an update somewhere; MSFT/Windows Updates perhaps, there's been quite a number of them recently.

Have you tried updating the motherboard chipset drivers?

 

Well that's odd. My mobo is a GIGABYTE 770TA-UD3 and when I go on their website and download the official chipset drivers I get ATI Catalyst instead :confused

http://us.test.giga-byte.com/Suppor...oductID=3284&ost=windows^®+xp+64bit

 

I would sandra's hard disk benchmarks and compare them with the reference scores at your manufacturers websites.

http://www.majorgeeks.com/SiSoftware_Sandra_Lite_d92.html

In sandra go to benchmarks,physical disks,then run the read and write benchmarks,to do this click the blue refresh arrows at the bottom.

So make note of the read/write speeds 'mb/s' and random access time 'ms' then compare them with stock.