Memory testing: 4MEM/5/40000006:B:O:C:O:R:D error

Hello everybody, we just bought two pairs of Kingston 2 GB (2x1GB) DDR2 800 (PC2 6400) ECC Fully Buffered (FB) Dual Channel Kt Memory for our MacPro.
After installing it crashed when it reached some considerable amount of work. We run the Apple Hardware Test (v3A146) and it found this error:

4MEM/5/40000006:B:O:C:O:R: D (this last space before D was intentional due to ": D" without space is a smilie --> )

I google it without great results (just similar ones).
Does anybody know what does it mean?

Thanks!