This article was previously published under Q320842
When you use Outlook, you may experience any one of the following symptoms:
When you try to create a new task or appointment, you receive an error message that is similar to the following error message:
Could not complete the operation. One or more parameter values are not valid.
When you try to exit Outlook, you receive an error message.
When you open a message in a new window, the menu bar and toolbars are missing.
This problem may occur if the profile or data files that Outlook uses are corrupted.
To resolve this problem, follow these steps in the order in which they are presented.
Part 1: Create a New Profile
NOTE: Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.
Click Start, and then click Control Panel.
If you are not in Classic view, click Switch to Classic View, and then click Mail.
Click Show Profiles.
Click to select the Prompt for a profile to be used check box.
In the Profile Name box, type a descriptive name for the new profile, and then click OK.
Click Add a new e-mail account, and then click Next.
Click the appropriate server type for your new e-mail account, and then click Next.
Follow the on-screen instructions, and then click Finish.
NOTE: Make sure that you specify a new Personal Folders file (.pst file), and do not use the existing file.
NOTE: Because you do not use the old .pst file while you are troubleshooting, you will not see any of your old .pst folders or files.
Part 2: Rename the Outlook Data Files
Outlook automatically replaces the Extend.dat, Outcmd.dat, and Frmcache.dat data files if they are missing. To rename the data files and then test to see if the problem is resolved, follow the steps that are appropriate for your operating system.
NOTE: Outcmd.dat stores any custom changes that you make to your toolbar buttons. If the problem is resolved after you rename this file, you must make the custom toolbar button changes again.
Microsoft Windows 98 or Microsoft Windows NT 4.0
Quit all Microsoft Office programs.
Click Start, point to Find, and then click Files or Folders.
In the Named box, type extend.dat, outcmd.dat, frmcache.dat.
In the Look in list, click your local hard disk.
Click Find Now to search for the files.
The default locations for these files are in the following folders
where drive is the drive on which Windows is installed.
NOTE: If you use profiles, these files may be located in your Profiles folder.
For each file that appears in the Search Results dialog box, right-click the file, click Rename, type a new name for the file (for example, type extend.old), and then press ENTER.
Close the Search Results dialog box.
When you are prompted, click the new profile.
Create a new task or appointment to see whether the problem is resolved.
If the problem is resolved and you use a .pst file in the new and old profiles, change the new profile to use the old .pst file, or import the contents of the old .pst file into the new .pst file.For more information about how to create a new set of .pst files, click the following article number to view the article in the Microsoft Knowledge Base: