I found a few solutions for your issues and a couple of links that should have you fixed up in no time!
- Find the folder that outlook is using for its temp directory and clear it out.
- Create a new temp folder for outlook.
- The system does not support long file names (unlikely).
Both 1 & 2 involve either reading the registry or modifying it. But the solutions look to be fairly easy to implement.
In our case, it involved deleting the files in the outlook temp directory.
I was able to resolve this by deleting the Local Settings folder from the user’s profile. I guess one can be specific and delete the Local Settings\Application Data\Microsoft folder (or even deeper), but since this was a profile that I copied over from another machine, I figured that it is better to allow the computer to recreate this again completely.
- Open REGEDIT.EXE and go to Edit -> Find… In the Find dialog box type “OutlookSecureTempFolder” without the quotes and locate that registry key.
- That key will contain the actual folder location, and will look like: C:\Documents and Settings\%USER_NAME%\Local Settings\Temporary Internet Files\OLK#\ (where # is a random letter or number)
- Copy the location of that folder.
- Click on Start -> Run… and paste the folder location from step #4 then click OK.
- Windows Explorer will open that folder. Please, delete all files present.
- Restart Microsoft Outlook and you should be able to open your attachments.