Render tab > Output > RGBARender tab > Shading > Alpha > Straight Alpha
OMG MORE UNORIGINAL STUFF YAY-kickassAk-
OMG MORE UNORIGINAL STUFF YAY
Try both thing I list here, cause I don't know which one of the two it is.1) Go into edit mode and select everything with "a" then press ctrl-N2) Go inot edit mode and select everything with "a" then press "w" and select "remove doubles"Hope that helps