Briefcase and orphans

I am trying to use the Briefcase feature on a laptop with Windows XP Home.
When I try to drag into the briefcase the My Documents folder, I get an
"Update Briefcase" dialog appear for most of the files which states, "[file
name] will not be updated because its merge handler cannot be loaded."

Furthermore, although I can't remember at what point I saw this, but I was
also given a message at some stage that the files were orphans???

Although I regularly use briefcases on my desktop computer and have done so
for some years successfully, this laptop is giving me some grief!
Can anyone help me with this?

Rob