After taking a look at your manual it seems your right, pretty shocking on MSi's part.
Looking up the beep codes in their technical section online indicates this:
3 short beeps: Base 64k RAM failure
1 long 2 short: A video error has occurred and the BIOS cannot intialize the video screen to display any additional information
I'd start with trying to re seat the RAM, then try just one stick, then just one stick but the other one, see if that gets you anywhere.