Are you getting this error is Outlook:
Cannot open this item. Cannot create file: ……….. Right-click the folder you want to create the item file in, and then click Properties on the shortcut menu to check your permissions for the folder.
If you are then the problem is the temporary Outlook folder used for storing files has filled up. You need to empty this folder and everything will work properly. The problem is that it’s no easy task! Because the folder is randomly named.
You need to use the registry to find the location of the folder and then manually open the folder up and delete the files.
However Here is a link to a small program that will simplify the whole process.
It’s provided by www.howto-outlook.com
Hope that helps!