First of all i suggest u test your memory, download this:
Ultimate Boot CD - Overview
It's a very nice testing tool collection, boot to this disc and run memory tests (memtest86, etc.).
Really looks like u have faulty memory stick, if it so, just remove it, and run the tests again to ensure that the remaining one is OK. Also pay attention while installing the sticks to the mobo, that they sit well and in order that is recommended by ur mobo manufacturer.
And for the BIOS flashing just download the latest version and flashing tool from motherboard manufacturer's website. And just follow the instructions.