IDE Editing Headaches

I have been plagued by a particular editing problem on my current
project. It involves making global changes within Selected Text. I'm
using BCB5 and have never had this problem before.

When I select multiple lines of code, hit <Ctrl>R, and use the default
options of Selected Text and Entire Scope, very often areas outside the
selected area get changed! This is _very_ annoying.

Is there a fix? Is it possible I've done something to cause this
problem? If so, can whatever I've done be undone?