At 1024x768x65k the default ATI drivers that shipped with Blue Spine Warp Connect yielded 'empty' Dos boxes - the windows would paint but no cursor prompt ever appeared. The solution is to 1. Reset the VGA on the recovery screen (Alt-F1 at white box) 2. Install Mach64 enhanced drivers (at least v2.0)
Every once in a while I still get video corruption after running a seamless windows session (this is quite rare), which I fix by opening and closing a full screen DOS box.