The Remote Access portal was updated on 1/7/11. After the update, two new plug-ins for Internet Explorer are required. After you login to the portal, you should see two prompts to install these plug-ins. Click Allow for both. If you do not see these prompts and the Remote Desktop session does not launch, then follow these steps to resolve:
1) Go to your Add/Remove Programs in your Control Panel, and look for Juniper Terminal Services Client. Uninstall this application.
2) Then click this link, and run the application. Go through all the prompts until finished.
3) Reboot your computer and try launching Remote Desktop again.