New User needs help with opening recent files

Hello. I'm using a rather older version of Filemaker Pro (5.5) on a
WinXP system. Here's my dilemma:

I installed the app from the CD I obtained. As I've tried to move to
more portable apps, I decided to copy the Filemaker folder over to
another location on the disk and access it through Portable Apps menu.
Hooray, it works fine! I was just delighted.

One thing, however, seems to have become disabled, and I don't know if
it's the result of moving the app to a folder other than that which it
was installed into. When I choose Edit, Preferences, Application, under
General, I have an option of setting the number of recently opened
files. When I click the box to activate this, I get the message, "This
command cannot be used by this installation of Filemaker."

It's not a fatal problem, but it certainly does slow me down in getting
my work done.

Does anyone have an idea of how to get around this? Thanks for any help
you can give.