Is this happening for all users, or through a specific account. If this is specific to an account, check the user account's group permissions.
Check to see if this is happening on other computer as well. Could be a cache issue. Try getting the latest jnlp file for Ad Hoc and latest version of Report Builder so that you are sure it isn't cause of an older file/version.
If the above don't work, as your company's supported user to open a case with ClientCare so that they can investigate properly. Do provide the relevant details and the steps to replicate.