Downloaded JAR content is corrupted

Hi,

I have an Apache 2.0.54 installation on Win XP sp2. The installation is
meant to serve Java Archive (JAR) file content for use with a third
party build tool Maven. The httpd.conf file is configured to set the
MIME type correctly for the content;

AddType application/java-archive .jar
AddEncoding application/zip .jar

However some of the JAR files that are being downloaded are corrupt (the
file size is correct, but they cannot be opened). Looking at an MD5 hash
the download process has clearly modified the content. The unusual
aspect is that this does not happen consistently. The problem only seems
to manifest itself on larger JAR files for exaple those > 100K.

Has anyone seen this type of behaviour, and or know what might be
causing it?

Thanks and regards,
Andrew