Lite-On LH-20A1S disconnects from SATA under load

Hi, hope somebody can shed some light on this problem.

System:
Intel E6600 CPU
4 x 2GB Crucial Ballistix Tracer PC2-6400 memory
Asus P5E-VM HDMI (0604) motherboard (onboard graphics not used)
2 x Hitachi HDS725050KLA360 (K2AOAB0A) HDD in RAID-0 on Intel Matrix RAID
Lite-On LH-20A1S (9L09) DVD-RW
Saphire ATI HD 2600 XT 256MB VGA
Vista Ultimate x64 SP1

When I first built this system it would sometimes just hang, the screen would turn off, and a cold boot was required.
No bluescreen, no dump, just a hang.

When running with a kernel debugger attached, and the dumps were inconclusive, always a different problem in a different area, typical of bad memory or overclocked systems.

Since I was not running overclocked, I upgraded the 4 x 1GB Crucial Ballistix PC2-6400 with 4 x 2GB Crucial Ballistix Tracer PC2-6400.

For a few months things seemed fine, so I figured it was the RAM.

Last week the problem started again.
Again I attached the kernel debugger, and again the dumps were inconclusive.

But this time I noticed that even after the debugger broke in, I could resume, and then the screen would turn off. When this happened I also noticed that the Tracer memory lights were still flashing, as if something was still running and the hang was not really a hang, but I could no longer break in with the debugger.

Today I noticed that while ripping a DVD with DVDFab the screen would just freeze completely, not turn off, just freez, and I had to cold boot.

This happened every time I ran DVDFab and the DVD was seeking, maybe a scratched spot or layer break, the machine would freeze.

After the third reboot I noticed that after a few seconds of hanging the HDD light would come on, and then go off again, when I pressed Ctrl-Alt-Del I saw a message reported by the Matrix Storage Manager software tray icon reporting that a SATA port had disconnected.

After a few minutes the system became responsive again, but without the DVD drive.

The NT eventlog reported this:
“The device ‘LITE-ON DVDRW LH-20A1S’ (IDE\CdRomLITE-ON_DVDRW_LH-20A1S__________________9L09____\4&36887771&0&0.1.0) disappeared from the system without first being prepared for removal.”

Running the Intel Matrix Storage Manager utility the DVD drive was no longer connected.

So, I am wondering if the problems may not all along have been something with the DVD drive, SATA controller, firmware, or driver.

For now I am running with the DVD drive disconnected.

Any suggestions, do I replace the DVD drive, how do I diagnose?

Thank you.
P.