Outlook 98 – form display error – HELP!

Our users use an Outlook form for their timecard. No changes have been made to the form or any other forms stored in the Organization forms. 4 users to date, are unable to open form receiving error “The form you selected could not be displayed”. Wehave installed the form in the personal forms and deleted it forcing it to reinstall locally but it won’t work this time. Please give us any ideas you might have. We are worried that by Friday we will have a major problem on our hands. Thanks!