I'm on 64-bit Windows 7 and having the same problem.
I have 700+ FLAC that I want to convert to MP3.
What I've done to get around the problem is this:
1. Load all the files into WinFF - I searched for "*.FLAC" in my music
folder and dragged & dropped all files into the program window
2. Clear the "Output Folder" location, so that it's empty
3. IMPORTANT: Choose "Display Cmd Line" from the "Options" menu
4. Set the "Convert to" and "Preset" options - Audio and MP3 in this
instance
5. Click "Convert"
This should open a window with all the Command Line details. Copy it
to the clipboard and close the window.
Paste the text at:
http://gskinner.com/RegExr/
Change to the "Replace" tab.
For the first (match) expression use:
"(.+?)" -y -i "(.+?)\.(.+?)" (.+?) ".+?"
Make sure that "Global" is checked.
For the second (replace) expression use:
"$1" -y -i "$2.$3" $4 "$2.EXT"
!! NOTE !! : Change EXT to whatever extension you require.
$1 = The path to ffmpeg.exe
$2 = The full path to the file(s)
$3 = The extension of the input file(s)
$4 = Conversion parameters/options
You can then copy & paste the new text into notepad and save it as a
BAT file, then run it.
I should also add that I offer no guarantees here. But it worked for
me.
Make sure that the match works and that the new text is what it should
be. Then copy & paste into a plain text file, save as "convert.bat"
and run it. It should run as it normally would through WinFF.
There's also an extra line at the end, where the BAT file that WinFF
creates is deleted, but since it doesn't exist it can't be deleted, so
you can safely remove the line, or leave it in, it shouldn't cause any
problems.
Hope this helps.