Clipboard Problem

I am running a macro in Word which creates mirror image Odd & Even Headers & Footers, i.e. the left & right parts of the even headers & footers are swapped over compared to the corresponding odd ones. To do this, for example, I cut the applicable left header part & then paste it to the right header part. When I run the macro, certain headers are blank. However, when I single step through, it works perfectly. Is it possible that when I run at normal speed, the clipboard is being cleared? Would it therefore be better to store the text in a buffer rather than in the clipboard?