whites shift when rendering with broadcast safe filter

Hi there,

I haven't encountered this problem before. I've applied the broadcast safe filter to every clip in a wedding video shot on DV with a superwhite Canon GL2. Most set to 'normal', some 'conservative', etc. Everything looks good in the scopes and with the range check on. Then when I render -- set to 8 bit YUV rendering, white, best -- the whites shift and I am back with the same problem. If I open the clip and deselect the filter, then select it once again, the now unrendered footage again appears perfect. When I re-render, it throws the whites past 100. What's going on?

SC