I hope someone can help with this!

After completing a successful small scale trial of Zimbra 4.5.5 with no real problems/issues we have gone ahead and rolled out to a larger group of people.

All accounts have been using Outlook either 2000 or 2003.
In order to use the zcsImportWiz (verison zcsImportWiz-4.5.5_GA_831.exe) tool we have converted all .pst files to 2003 format. No issues converting all documents/attachments are fully accessible.

zcsImportWiz tool ran with no errors. Now all attachments are showing as corrupt, this includes .doc, .xls, .pdf etc.

Has anyone else experienced the same issues using the Import tool?
What and why is it happening?