If you are unable to get into Chat and use Internet Explorer it is likely caused by having Pop Ups blocked. You need to disable the Pop Up blocker for Chat to work.

On your Internet Explorer menu bar go to Tools, select Internet Options and when that box comes up click on the Security tab.

If the Internet zone is not already highlighted click on it (it's a globe image). Click on the Custom level button. Scroll all the way to the bottom and then slowly scroll up a few choices and look for Use Pop Up Blocker, click the the round button next to the disable choice. Click OK and the box closes, then click OK on the next box too. You might need to restart your computer if it asks, if you have any unsaved work re-start later.

Know that disabling Pop Up blocker is not a desired choice but may let you get into Chat.