There is a known bug that sometimes causes this to occur. In the Express plugin, click the Settings link near the top right of the plugin and see if "Use a proxy server to connect" is checked. If it is, follow the steps listed below to fix the issue.
- Go into the Settings screen and uncheck the option “Use a proxy server to connect”
- Click the Logoff link at the top right of the form
- Close PowerPoint and then reopen it.
- Go to the PresentationPro tab and click Search Designs to open the Express plugin.
- Here’s the trick that fixes it…On the Welcome screen, fill in your email address and password. Then you need to check and then uncheck the proxy option. Put a check next to “Use a proxy server to connect” and then click it again to remove the check. The rest of the fields underneath should disappear.
- Click login at the bottom. Now go to the settings screen again and the “use proxy server to connect” should be unchecked.