Need Advice for a Few Problems

[sabwafare2001]

MSI K7N2 Delta-ILSR
XP2500+ w/slk-800A & Tornado
2x512mb cosiar PC3200 Ram
2x100GB/1x120GB HD's all WD 8MB cache
ATI 9500 Pro
Emermex 460W PSU
Lite-on 52x24x52 CDRW
Nec 1100A dvd+r/rw

I have a few questions:
1. What the does, Device\hard disk 2\D - disk not ready to access, error mean? I always get this error eventually when I overclock. Usually whats happens is a program will not close or hang, then my comp. crashes. When I looked in the event viewer, it records the error stated above. I have 2 hd's on channel 1 & the other, 120gb on channel 3. It happens when I set it anywhere from 2.0ghz to 2.1ghz or 190 to 200. I also have my multiplier set at 10.5. My vcore ranges from 1.63 to 1.68. When I raise it, the same result happens. My temp ranges from 31C to 37C. Does this mean that the disk is going bad or is this the result of overclocking & how could this error be fixed?

2. Currently I have some 1x512mb cosair pc3200 twinx platinum ramsinks and 1x512mb cosair pc3200xms black ramsinks. When I run that sandra soft software and look at the mainboard & bios info. At the memory section the cosair twinx reads: 1x512mb 3200..........CL2(CL2 up to 200mhz & CL2.5 up to 200mhz. The XMS reads: 1x512mb 3200.........CL2.5(up to 167mhz). The numbers in between are the same, just the end is different. My first question is will the XMS hold my back in oc'ing? I can run both at CL2. When I took it out I was able to boot into windows at 200mhz X 10.5, but when I had it in I was not, it stopped the windows loading screen. If I took the ramsink off the, supposingly XMS, what should it read on it, #'s & letters? What should the settings be for the ram 1 or 2 sticks?

3. Why when I run the cpu benchmark in sandrasi soft, the AXP2600 & AXP2800 score higher than mine if I'm at 2.1ghz or 10.5x200? What could I do to increases the performance or what setting would yall recommend?

[ArcticFox]

1. Don't know

2. No it won't

3. 2.1Ghz is 10.5x200. As for scoring higher, I only have my experience with my 2500+ and it runs great on a 400Mhz FSB and at 2.00Ghz. From what I gather, it should score the same because they are the same, or am I not understanding you correctly?