Larry mate I wopuld at least update the chipset and the SATA drivers from this site
P6X58D-E | Motherboards | ASUS Global
Now working in the dark here a biut so can you please disconnet al;l drive exacpt the OS C: drive and wee if this happens when you do that .
If it does then I would suggest you do this and in any case do it anyway.
MEMTEST
Now to make absolutely we are on the same page the memtest linked here is the only one we recommend and it MUST be run for at least 8 passes or you may as well not bother. It is rather lengthy and best left for a downtime for that machine - overnight is good. Having said that you can stop the test if errors show up while you are around and then it is a matter of tracking down the bad stick of RAM.
RAM - Test with Memtest86+ - Windows 7 Help Forums
(This is pretyped to save time)
Plus I see you are running what would seem to be a minimum of RAM and could you just check to see if the RAM sticks are all labelled the same preferably the same brand but more specially the speed - MHz and the timings (again your RAM is the slowest speed supported by that board). This is because if the timings are different along with the frequencies it can cause your system to become unstable.
Now you can do that or use my little ditty for checking each stick - use PART B:
Using HW Info
PART A:
You can test the volts on the PSU with HW Info
HWiNFO - Download < download the right bit version and close the right hand window select Sensors and scroll down to the power section where you will see what the volts are doing see my pic. In my pic the section (Nuvoton) with VBATT as a dead give away you are in the section for the rail voltages. There are other section titles and one that pops up often is ITE (sometimes the usual one for Gigabyte boards)
Now the voltage on the different rails have to be within 5% =+/- of what is required or the machine will not work properly if at all.
Limits +/- (minimum - correct - maximum)
12v1 = 11.4 - 12 - 12.6v
12v2 = 11.4 - 12- 12.6v
5v = 4.75 – 5 - 5.25v
3.3v = 3.135 – 3 – 3.465v
-12v = -10.80 - -12 - -13.20v
+5VSB = 4.75 – 5 - 5.25v
The Power good signal voltage at pin 8 on the 24 pin plug (grey cable) should be the same as the 5v rail reading/s
See this for the rail voltage info
PSUs 101: A Detailed Look Into Power Supplies (Section 2.)
The original right hand window shows the machine running and is handy for that but for looking at the components in some detail close it and use the main left hand side panel
FOR OTHER COMPONENTS
PART B:
Open each small square with + in it on the section the components are in and then click on the individual component/s (it will highlight in blue) - in the right hand side will appear all sorts of details including brands speeds and other essential info that particular device. See pic of mine for example.