Attachments from China in Outlook 98 Garbled

Our company has Outlook 98 running on all of our PC’s. We receive emails with attachments from China. On most PC’s the attachments can be opend and read, but on a few these attachments are embedded in the email message and are all garbled. It looks like they come in with a language type of big5. Is there some option or addin for Outlook that needs to be set to be able to format these correctly. Seems some PC’s have more Language selections when you choose Format>Language then others but I don’t know where this get setup???