People using Vista's Windows Mail program may run into a 'Message could not be displayed' error when they try to open a message in their inbox. What's worse, you may be prevented from moving or deleting some messages--and having phantom messages in your outbox could block other mail from getting out.
The easiest and safest fix works only in mail folders that you create yourself, not in the standard folders like Inbox and Outbox. Move all of the good messages out of the folder, right-click it with the ghost mail still inside, and select Delete-Yes. Instead of deleting the folder, this operation deletes one ghost message. Repeat the steps until all bad entries are gone.
Things get trickier if the ghost message lurks in Inbox, Outbox, or another folder whose Delete option is grayed out. First, back up your Windows Mail directory, which is probably located at C:\Users\yourlogon\AppData\Local\Microsoft\Windows Mail. (To find the path to this directory in Windows Mail, select Tools-Options-Advanced-Maintenance-Store folder ). Once you've found the directory, close Windows Mail (very important) and copy (not move--also important) that folder to another location.
After you've backed it all up, download, unzip, and launch the free utility WMUtil. Click Repair Database-Clean Blank Files . If you have ghost messages in Outbox, click Clear Outbox . Close WMUtil and reopen Windows Mail to see whether the fix worked.
If it didn't, your next step is to delete your mail directory, but only after backing it up. In the original Windows Mail directory (not the backup), delete the file WindowsMail.MSMessageStore. Then go to Windows Mail's Backup\New subdirectory and delete WindowsMail.MSMessageStore again.
Relaunch Windows Mail and wait about an hour for it to place your messages in subfolders of a new Recovered Messages folder. To be safe, close and relaunch Windows Mail before you drag your messages and folders back to their original location. You might have to do some significant reorganizing at this stage.
If this repair effort messed things up hopelessly, close Windows Mail, delete the original Windows Mail folder, and move the backup to the original location. Then you might want to consider migrating to an alternative mail program, such as the free Mozilla Thunderbird.