There's a bug in MSFT's filer.scx (which emulates VFP 3 and FPW "Filer" command)
The init event of this form contains...
ON SELECTION BAR 21 OF _mtools DO FORM &cFilerPath.
Simply amend this to...
ON SELECTION BAR 21 OF _mtools DO FORM "&cFilerPath."

The problem is that the original code does allow for path names which include a space; like "C:\Program Files\VFP"

BTW - a great advantage of Filer over the old filer is that you can run it any number of times concurrently allowing multple searches to be carried out in the one session without loosing your place in a search and replace sequences. So I can multitask :-)