By finding this I’m gussing you and I are having the same problem.
The problem being that your trying to open an email attachment in outlook and it’s throwing up the error “cannot create file”.
Here is a quick and easy way to sort this:
#1. Click Start > Run and type regedit.
#2. Click Edit > Find and type OutlookSecureTempFolder.
#3. When regedit has found the entry, it will tell you where your Outlook temporary files are stored. It will look similar to: C:\Documents and Settings\username\Local Settings\Temporary Internet Files\OLKrandomnumber
#4. Open My Computer go to the location you just found above.
#5. Delete (or move) all of the files in this folder.
#6. Restart Microsoft Outlook and try to open the attachment again.