Sounds like screen tearing, which happens with moving objects in Trainz when Vertical Sync is not turned on. Do you have an ATI graphics card? If so, try turning on vertical sync in either the ATI Catalyst Control Center or in the Trainz option panel before you start the program. Try Vertical Sync: Full Rate and the Frequency: 60. That's what it is for many LCD flat panels and a lot of CRT (big bulky) monitors. My ATI 4850 does the screen tearing if vert. sync is off.
