Outlook Express will not download

I’m running XP Pro with Outlook Express 6.
When ever I try to download a file it will start and then during the 1st or 2nd file will bomb out telling me an unknown error has occurred.
IT also is telling me with every file that a recepit could not be sent.
MS Outlook is working fine.
All my antivirus is up to date and I have done a full virus/ad scan, all clean