Today Microsoft is releasing an update to AD RMS to completely remove the “application manifest expiry” feature. This update is particularly important for AD RMS customers using Internet Explorer, because the certificate for the RMA add-in for Internet Explorer will expire on February 22nd. The RMA add-in for Internet Explorer allows users to view content with restricted permission in Internet Explorer. It is critical that these customers install the update before then, in order to avoid any issues accessing or protecting web-based content.
For more details, you can read the recent blog post on the Microsoft Forefront team blog.
If you download and install this AD RMS client update, the update built specifically for Microsoft Office applications (released on December 11, 2009) is not required.