preduk,
I had exactly the same problem with an ASUS motherboard. Said it supported 2 x 1GB modules in the manual but turned out that it didn't.
ASUS admitted that they were aware of the problem, but would never do anything about it, such as provide a firmware upgrade. Perhaps it couldn't be cured by a software update. I don't remember.
But it has certainly made me think twice about buying from ASUS again.
SD