Got a weird one today. By default the line width on a new copper pour outline(CPO) was 0. Before I cottoned on and changed it to 5 thou, I was getting copper poured all over some tracks and some ICs; straight over the top - no clearance at all -obliterated.
When I noticed that older CPOs were 5 thou line width and didnt have this problem I changed the line width and everything was hunky-dory.