I figured your BB Attachment Service is running because you stated other devices are able to open attachments.
Blackberry Attachment Service
To install the attachment service, follow the instructions below:
Cradle your device. If you have a password enabled, you must enter it before your device will connect to the desktop.
Open the BlackBerry Desktop Manager, double-click Application Loader, and click Next.
If prompted, enter your password again, then click Next.
In the Application Loader Wizard window, make sure the box next to BlackBerry Attachment Service is checked. Click Next, then Finish, then Close.