I dont think its a problem with your Xenarc. I have the M10000 board and have had this problem myself with a k301 screen.
There are two different locations on the VIA site to download two different, but compatible display drivers for the m10k.
Under the "Support" tab, you can get drivers from "Drivers at VIA Arena" and "EPIA/VB Downloads". Try the two different drivers. Thats how I fixed my problem.