Error The open form action was cancelled

Database with Access front end and SQL backend. Some PCs click on command button to open a form and receive the following message: “The open form action was cancelled. Used method do.cmd object to carry out an action in Visual Basic but then clickedcancel in a dialog box.” (the only thing the user clicked on was the original command button). This only happens on some PCs, other PCs use the form without error. It does not seem limited to PCs with a specific version of Windows (happens on both Windows 95 and 98). There do not appear to be any references missing. Any suggestions?