Hi, Rob,
Like most large Windows programs, Word uses a ton (that's a scientific term
<g>) of entries in the Windows registry. Some of them are fairly easy to
understand -- some store options that you set in the program, or tell
Windows that Word is the standard program for opening certain kinds of
files. Others are intelligible only to programmers, such as the class
entries that control access to COM interfaces in the common Office DLLs.
When you re-register Word, you tell it to repeat the process (originally
done during installation) of writing the standard values of those entries.
By design, this doesn't change the options settings, but it does rewrite
everything else.