A customer of mine sometime gets the error message 'The operation failed'
when opening an attachment. This has been seen for .xls and .zip files from
a particular source. If outlook is closed then re-opened, the attachment
opens fine. Also, if the same file is sent again, the copy will open.

I posted this message once before and it was suggested to me that there may
be a problem with the secure outlook temp folder. I have followed the
instructions given to empty this folder, but this has not resolved the
problem. Even directly after emptying the folder, the customer experienced a
problem opening an xls file. I have since been told that the problem is more
extensive than first thought with other file types, notably jpg and pdf
files, also being affected.

Any further ideas?