[Vorbis] Help with OggDrop error please

[Cicada Music]

Hello,
When I drop two wav files on the OggDrop box (separately), one converts 
as expected but the other gets the following error message:
"Warning: Unexpected EOF in reading WAV header"

When I drop two wav files on the OggDrop box (together), one converts as 
expected but the other gets the following error message:
"Warning: Unexpected EOF in reading WAV header error is invalid argument 
(22)"

I've tried using both of the following versions with the same result:
-oggdropXPdV1.9.0-1.3.2-generic
-oggdropXPdV1.9.0-aoTuVb6.03

I am using Windows XP Pro SP3, and the wav files are 44hz, 24b, stereo.

Your assistance is greatly appreciated!

Thank you very much,
Spencer