Trying to trim some HD .mov clips

Lion 10.7.3

I have some movie files from my canon 550d.

They are: h.264 1920 x 1080 .mov files.

I need to do some basic trims here and there, so was hoping to use quicktime trim to help out.

Trouble is it always either crashes or gives an unknown error on export. I've tried various export options with no luck.

Anything I'm doing wrong here? Unsupported file format or something ( it plays back just fine ) ...?

I must add, this works fine on windows 7 using quicktime pro, using the same files. Just a bit unconvenient for me.