Recuva 'unable to determine file system type'

Hi.

I use Windows 7 64-bit and am reading a 1GB xD memory card via a USB card reader.

When I came to transfer my pictures into my computer, Windows 7 initially recognised the files and listed them all in Windows Explorer. However, when it came to move them, the first 4 or 5 transferred and then it stopped. Now Windows won't read the card at all and as soon as I try to access it, it asks me to format it.

Using Recuva, I selected 'In a specific location' but Recuva told me I needed to format the card.

If instead I select 'On my media card or iPod', I am told it is 'Unable to determine file system type'.

I have tried three other data recovery programs and they all find and display all of the missing pictures without a request to reformat - although, of course, they want me to pay to recover them.

Can anyone help, please? Generally I'm impressed with Piriform products but I can't get this one to work.

Thanks!

Rob