Could be your graphics card: I had this problem for a long time, before realising that the driver just needs updating. If you don't think its that, then check there are no lights directly next to or above the model.
Also: To single out your graphics as a problem, use the SET OBJECT command to make your object insensitive to light. If its still white, then it could be your graphics.
Hope this helped, but I feel strangely under-qualified to be advising people about their problems, so I could be wrong.
David (Lightning Studios)
P:2.4ghz /HD: 120 GB/ GeForce FX 5600 128meg / WinXP Professional SP2