Outlook not opening attachments

I have several NT machines that are running Service Pack 6a and they also have MS Office 2000 w/ the SR1a patch installed…

Problem is when the user goes to open an attachment that comes in with an e-mail in Outlook…Outlook says it can’t find the file to open the attachment…

For example…If I click on an attached Excel spreadsheet it won’t open the speadsheet unless I have Excel running first…