Cannot select some edges in detail view

When I create a detail view in drawings I am unable toselectcertain edges. In the parent view the edge can be selected,but inthe detail view when the mouse is over the edge it isnothighlighted.

I have tried rebuilding the drawing and model, re-openingthedrawing and even rebooting my computer but with no change.Theproblem has occurred in several drawings. Any ideas on whattheproblem might be?

My system is:
Pentium 4 3.00GHz
1GB RAM
NVIDIA Quadro FX 540
Solidworks 2006 SP5.1

Thanks,

BenSolidworksDrawings And Detailing