can someone please help me with this problem

I recently bought a new computer:

P5W DH
E6600
2 gig PC6400 corsair
74 gig raptor
250gig seagate SATA 2 16 mb
antec NEO HE 2.2 550W

When i first got it it would randomly restart everynow and then. I thought it was teh RAM and raised teh voltage from 1.8 to 1.9 with no luck.

recently (since i plugged my G15 in yesterday) its bene doing it 3 times as often. 4 or 5 times today so far. I've got 2 messages on start up now
first one :

- No IDE Master HDD detected (i dont ahve an IDE at all..)
-Overclocking failed OR overvoltage failed (havnt overclocked just raise RAM voltage by 0.1)

second message:

-3rd Master Hard disk error
- No IDE master H.D.D detected

does anyone know what my problem is?
thanx

Yeah, go to Optimized Defaults...

Or try a BIOS update:

http://support.asus.com/download/download.aspx

~Ibrahim~