I've been dealing with this issue for a few days now. I received a couple games as gifts and every time I click on the notification I'm brought to the redeem page, and the box is completely black. I try doing it through the email and it says its been added to my library, but when clicking on the 'yes I have Steam" button I'm greeted with "Failure: an error occured while installing appID 0 Connection timed out" on my Steam client.

I also can't view my wishlist, which I see a lot are having issues with too. I'm afraid they're related.