Blinking lines on model after lightmapped?

Hi, After i made a model using GoogleSketchup, i imported it into unity and lightmapped it. When it is completed, blinking white lines could be seen in the edges and vertices of the model. Here's a screenshot of the model with lines : http://yfrog.com/mc53218454p Can anyone tell me what made this happen and what can i do to make it disappear? THaks in advance!