<p>This is specific to neither Chrome, nor for periods in tags. You just have a few ignored tags that are hidden for you. This was confirmed using IE8 with <a href="http://stackoverflow.com/questions/tagged/super" class="post-tag" title="show questions tagged 'super'" rel="tag">super</a> (that I just found on the front page).</p>

<p>It's simply a matter of how ignored tags work when you have "Hide My Ignored Tags" set.</p>

<p>If you are performing a tag search only (as in, the only search terms are [tags]), then it temporarily overrides the hiding functionality of any such tags <em>specifically in your search</em>. This way, if you have for example <a href="http://stackoverflow.com/questions/tagged/java" class="post-tag" title="show questions tagged 'java'" rel="tag">java</a> ignored, then it doesn't show you absolutely nothing when you explicitly search in the java tag. Note that if you are fiddling with your preferences on the questions page, it may require a refresh to get visibility back. </p>

<p>However, if you perform a normal search or a compound search (as in, there are non-[tag] search terms), then it will behave as normal for the system - it will hide all questions with that tag. Naturally, this results in nothing when you are doing a compound search with that term.</p>

<p>I'd suggest either removing the ignored tag (if you don't actually want to ignore it), or otherwise disabling the "hide" option. <a href="http://meta.stackexchange.com/questions/36735/temporarily-disabling-ignore-tags/36737#36737">There is also an open feature request</a> for allowing easier access to disabling the hiding functionality.</p>