subject: Resolving 'this Program Has Performed An Illegal Operation...' Outlook Express Error [print this page] Outlook Express is one of the most widely accepted e-mail client, used by professional and home users. Outlook Express 5.0 and later versions use *.dbx file format for storing individual folders that you see in local folder list. Sometimes, when these *.dbx files are marked as read-only or are corrupted, Outlook Express finds it unfeasible to locate and/or read them. Some related error messages might appear whenever an attempt is made for starting Outlook Express. However, to resolve corruption issues, you need to either restore the e-mails from backup or use an Outlook Express Repair
