In case you are interested, I ran a test on my system. Taking the literal copy of FPW2.6 from my client's PIII 550 and installing it on mine, I ran it and FPW now seems to work fine on my machine. I don't know what the difference is, but there you go. Maybe I had an old version or a corrupt file. Quick view of both versions of foxprow.exe seem identical and WinDiff doesn't seem to find a difference. The only notable differences between both setups are the menu shortcut which doesn't explicitly name the config.fpw and the foxprint files in the system directory, both setups as per the client's machine and now on mine.
HTH