If resetting the refresh rate does not fix this and the D3D test fails, then reinstall DirectX6 core. If that fails you need to consider uninstalling any previous drivers. Look at my P urge page . The reinstall the Banshee drivers and DirectX6 core. There have been a few reports of DirectDraw test failures that were resolved when the Creative Labs Blaster Control monitor position and resizing control was reset to Factory default.
Video cards require an IRQ to do bus mastering.
It is not absolutely clear that the Banshee does bus mastering, although PCIList shows it doing so while Scisoft Sandra says no. Sorry, I do not have clear answer on this yet. Try the RAM swap. Who knows why this appears to work. If you have gone this far, and the card still fails to operate in DirectX or Direct3D, the card is defective and should be returned or exchanged.