Dave,

This typically happens when you delete an executionlink (yellow automation link) that has a breakpoint attached to it, without first deleting the breakpoint. 

The debugger thinks that the breakpoint is still existing, but is unable to find it, because the corresponding executiion link no longer exists.

Most find a remedy to this , by deleting all the breakpoints within the autx that is causing the error to display. 

Instead of re-doing the automation, I would suggest that you delete all the breakpoints in the autx, by doing the following:

Debug >> Delete All Breakpoints (using the file menu)