A user had this problem: "I am currently working on a problem regarding a filter applied to a specific e-mail folder in Microsoft Outlook. It appears that the folder has a filter applied to it but when I check the properties, it shows nothing regarding keywords. Also, there are only 11 e-mail messages showing on the screen, and 121 are supposed to be in there. Also, the folder shows the volume at 2.6 Megabytes and that there are 121 e-mail messages in the folder. However, I can only see 11. "

Someone suggested this would fix it:

Start Outlook from the Run dialogue:
outlooke.exe /cleanviews

While this is technically correct and will definitely fix the problem, it's like amputating your leg to treat an in-grown toenail. It's serious overkill and will delete every custom view you've created.

The proper way to handle the problem is first try a different view to see if the messages "come back". If so, you just need to reset the other view. This is easily done either from the Views menu - browse for the Define Views dialog, then select the problem view and click Reset - or Click (or right-click) on the row of field names at the top of the message list - select Custom (or Customize) then Reset. (Those are the general steps - the exact steps vary with the version of Outlook. See http://www.outlook-tips.net/beginner/viewmenu.htm if you need more help.)

Only if this fails or you have other problems that are attributed to corrupt views should you use the /cleanviews switch.