Today I had a user run into an odd error in Outlook while trying to open an .rtf attachment. “Can’t create file: repCarrierDispatchMaster.rtf. Right-click the folder you want to create the file in, and then click Properties on the shortcut menu to check your permissions for the folder”. This was a new one for me and right away I incorrectly assumed this was due to Outlook 2003’s attachment security settings. This wasn’t the case nor was the user’s anti-virus software at fault.

What caused the problem is the way Outlook saves temporary files when opened. It saves a copy of the attachment into the hidden Outlook sub-folder of Temporary Internet Files and appends that file name with a number sequence. The problem comes up when you try to open an attachment with the same name more than 99 times as Outlook will not increment the filename any further. That’s what trips this error.

To fix the problem you first need to figure out the name of Outlook’s hidden temp folder. Outlook creates a temp folder named OLK*** where *** is a random number. Windows Explorer hides this folder even if you have “show hidden folders” turned on. To find the folder open the command line from the start menu or by typing CMD from the Run box. You will start at the local user profile path. From here type the following and press enter:

cd “Local Settings\Temporary Internet Files”

Now that you are in the temporary Internet Files it’s time to find the hidden folder.

dir *.

This will list all folders and files without attachments. In my example you can see my folder is named OLK18. You can now either open Windows Explorer and navigate to the Temp Internet Files folder and add \OLK18 (substitue with the name of your folder) and remove all the duplicate files here or stay in the command line and just change directory with the cd command to the outlook folder and run del *.* to delete all the files within the folder.

Ideally Outlook should be doing some housekeeping and keep these files cleaned up.

UPDATE 10/22/08: Using a batch file to automatically clear this folder on computer startup.