By "after a while" do you mean after days and weeks or right after you installed WHS?
Does it report anything after you hard boot when this happens?
I've installed WHS on the D510MO about a week ago. No problems with WHS per-se. Problems with the board's CPU and fan monitoring and regulating. Neither are working correctly and that seems to be the consensus on here.
I hope a BIOS revision will sort things out and perhaps remedy what you are seeing.
I too have built a home server with the Intel D510MO and to begin with I had a few issues and found that I was better off using the out of box standard VGA driver instead of the drivers on the disk. As Windows Home Server is not supported on this board mostly Windows XP drivers work for LAN, Chipset and HD Audio. The VGA driver appears to work but can cause propblems when installed. As Windows Home Server is not a desktop operating system and is designed to be used in headless mode then I don't see a problem with using the standard drivers. Also make sure hardware acceleration is turned down to one notch as that can cause issues too. Since following these steps my home server has worked fine and is sharing media to my network right now