This problem usually occurs because an invalid JNLP file is used to initiate the Collaborate session. Usually this can be solved quickly by exiting from the Collaborate window, and trying to reconnect.
A number of people are being caught by the security in Internet Explorer.
After clicking the WebMeet link, there may be a small yellow bar that appears above the navigation bar for the course.
It indicates that the download was blocked and to click here for further instructions. Click the bar and choose Download File... Internet Explorer will then return to the course homesite. Click the Webmeet link again and it should then open the session.
To stop the information bar from blocking file and software downloads
- Click to open Internet Explorer.
- Click the Tools button, and then click Internet Options.
- Click the Security tab, and then click Custom level.
- To turn off the Information bar for file downloads, scroll to the Downloads section of the list, and then, under Automatic prompting for file downloads, click Enable.
- Click OK, click Yes to confirm that you want to make the change, and then click OK again.
This is a known issue with Java 8, the latest version. You will need to uninstall Java 8, and install Java 7.
Java 7 can be found here: http://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html