Windows 7 Repair Issues (big time!)

(Windows 7 Pro 64bit)

After assembling a brand new machine and installing Windows 7, all seemed to be going well and then for some reason I booted again and it came up with System Repair and could not repair it. So I decided maybe a power failure or something had trashed it. I did a complete reinstall of Win 7 64bit Pro. Things seemed fine again, but then eventually it did the same thing. On this machine I have tried the following:

• swapped my RAM. It didn't help. Both still show 8GB of RAM.
• Ran the memory tester in System Repair menu
• swapped the power supply for a better one
• performed System Repair (unsuccessful)
• performed System Restore (unsuccessful)
• Disabled CPI APIC support & set Plug and Play O/S = YES in BIOS per a newsgroup--didn't work
• reset all BIOS settings to factory defaults
• fixmbr
• fixboot
• SFC /SCANNOW
• Attempted booting to Safe Mode. I once got it to show the log of loaded drivers. It seemed to hang on classpnp.sys
• Installed Windows XP Pro 32 bit just to see--seemed to work fine
• RMAd the motherboard Asus P6X58D Premium, just in case...Installed that
• reinstalled Windows 7 (again)
  It seemed to be working, but today when I booted it up to try to work on it again, I got the Startup Repair. I let it run then it said the following:

Cannot repair this computer automatically
Problem Event Name: StartupRepair offline
Signatures:
01: 6.1.7600.16385
02: 6.1.7600.16385
03: Unknown
04: 22
05: autofailover
06: 1
07: Corruptfile
OSVER: 6.1.7600.2.0.0.256.1
Locale ID: 1033

I really have NO more ideas as to what could be wrong with this. Any suggestions? It seems an unreliable machine at best.

More info. This has an i7 920 processor, 8GB of DDR3 Corsair, Cooler Master case, ATI Radeon HD4670, a DVD writer, Western Digital WD500AAKS (500GB) hard drive.

HD Diagnostic gave me Unable to locate license agreement DLGLICE.TXT

memtest86 doesn't like my USB floppy. It says:
Can't figure out how many sectors/track for this diskette.

Are there any others that will test 8GB?

I downloaded memscope, but it only seems to recognize 4GB

Please fill out you system specs, lower left corner.

Make sure Win7 partition is marked Active before running Startup Repair at least 3 separate times with reboots. Partition - Mark as Active

Try System Restore from the DVD/Repair CD, not the F8 Boot Tools menu.

Open DVD/CD Command Line, use DISKPART to List Disk for DVD drive letter. Using the drive letter you identified, type:
D:
cd \boot
bootsect /nt60 SYS /mbr

If it won't start, you can copy out files using this method: Copy & Paste - in Windows Recovery Console

Then wipe the HD before reinstalling Win7: SSD / HDD : Optimize for Windows Reinstallation

I ran the Ultimate Boot Disk. It has memtest86+
It only showed 4GB instead of my 8GB, but after running for 2hrs and 37minutes shows the following two entries:
Tst Pass Failing Address Good Bad
=== === ============ ======== ========
5 2 000b88590c8 - 2952.3MB 00011000 00001000
5 2 000bc419028 - 3012.0MB 00011000 00001000

Does this mean my RAM is bad?

Well, it is RED that I quoted. Now in over 17.5hours, I have 2 counts of the second item listed.