SW2009 SP 5.1

I'm trying to add explode lines to a very simple assembly.  Somethnig I've done thousands of times with no problems.  Suddenly, SW has started making nonsensical route line paths that look nothing like the preview. Here is a preview:

Looks great.  And here is the resulting route line:

Not so great.

The problem seems to occur only with explode lines that are associated with holes normal to the axis of a cylindrical part.  The path SW chooses to create isn't always the same either.  Here are two more from the same assembly:

Here, the route line is attached to the edge of the hole in the green part, despite the cylindrical face having been selected.

And in this one, the route line follows the correct path initially and then decides to make a 90° jog to the edge of the hole.

Any thoughts?

Jim S.