Hi,
Looks like you all have solved this, but I wanted to point out a potential problem source, I think.
"It seems that in all cases the final regressor, dL (*.dfile[6]), is what is causing the problems. Take out that regressor all of them run fine."
As I understand the motion correction files, the columns are numbered 0-5, not 1-6, so referencing column 6 would be a non-existent column.
Again, without going back to the definitions of the files, that is what I remember of the numbering scheme,
-jim