Hi there
I realise the original poster has since more than likely deleted the file but in case it is of use to them or anyone else, I am having the same issue with files being corrupted, only from recordings made using Radioshift. As Radioshift records to my hard drive, abet in a folder that is hidden by default, and the files were large, I was fairly certain the audio still had to exist in the file somewhere.
It appears I was right, based on what I've read online. It seems that the issue is caused by the file headers getting corrupted. The header of each file tells computer what file type it is; how long it is and so on. What one needs to do is replace the corrupt header with a good header from another file of the same type and possibly same length.
This can be done using a program known as a hex editor. This I am currently trying to figure out so I can't be more helpful than that. Other than to say I found the following discussion thread very helpful in pointing me in the right direction: http://www.lfsforum.net/showthread.php?t=45156
Of course if your not technically minded and why should you be, then you may find this more difficult to look into. If it's really important though, I'm sure there might be companies out their who could recreate the header for you.
Kind regards