If your web browser blocks third party cookies, and you have previously added an exception for Collaborate, you will need to change your settings.
If Collaborate’s cookies are blocked, you won’t get any further than a spinning purple circle when you click on the Collaborate Webinars link in your Blackboard courses.
You will need to add the following domains to the allowed list of cookies
To see the list of blocked cookies, and to allow them, click on the padlock in the address bar, click Cookies, click Blocked. Then click on the ones that end in bbcollab.com and click Allow for each.