Arcanum image burning then black-out

[Twin Tattoo]

Used the No-CD download. Everything is fine but soon after I start playing, the game will start to burn out of image wherever the character moves (where the character's feet would touch the ground) then eventually just black-out the entire map. When I put the CD in, it's fine. But it is only fine for a little while without it. Have two computers and don't want to constantly sneaker-net the CD between them (saying I'm the only one playing ... which usually isn't) nor am I willing to buy two of the games. Anyone else have this problem? What's going on? Is there anything that can be done?