Well when I do your specs with Extreme PSU calculator I get 390Watts with 4 HDD (SATA) and 350Watts with 1 SATA HDD. (now that's CPU at 100%, so assumed having load like gaming or DVD Ripping and burning).
Even though the Thermaltake is a nice unit, at 430W it's running pretty much at 90% maximum power with 4HDD's in and 81% with only 1 HDD in.
It seems to me you might have overworked the unit with the 4 HDD in and now it's just a matter of time before she completely gives up. Also I'm a little concerned with the 18Amps on the 12V rail, that is really light for your rig. If you ever wanted to upgrade the 6600 to a 7800GT or higher forget about it with that PSU. My rig is an Athlon 64 3500+ with the MSI 6600GT, 1 HDD 10,000RPM SATA and DVD R/W and I blew up a 450W (12V@22A) generic cheapy in the first week I had it running. The AMD64's like power, they use near 100Watts alone, so at 12V that's 8.3Amps. Your Dual core will demand even more. i.e not much left over from the 18Amps to run the rest of the system.
For $40-50US can you get a 500W unit with 2X12V rails, each at 18Amps. Enermax makes some good models like that.
Well that's my theory, other's here might find something really specific in your minidump or you might expose a RAM problem with memtest.
Cheers.