If you are receiving this error message when you try to open an attachment to an email this might help. My problem was that I did not have the "Blackberry Attachment Service" loaded into my phone applications. Connected my phone to Desktop Manager and sure enough the Blackberry Attachment Service Box was unchecked. I checked the box and completed the add application through Desktop Manager and I was set. NOTE: The messages that I had received prior to adding the Attachment Service still gave the error message when I tried to open them. But all messages received after installing the Attachment Service opened without any problems. If this does not fix your problem search Blackberry.com forums they listed some other fixes for this problem. The one stated above solved my problem.