I added and removed some tags today on my meta account while testing something (I previously had no tags marked as interesting). Now, however, under interesting tags I see a blank box (same color as an interesting tag would be), followed by the 'x' button to remove it. The tool tip for the "tag" says "see all questions tagged ''". I click the 'x' to remove the tag (or remove it from my preferences), but as soon as I load a page displaying the interesting tags, the blank one is back again. I have tried this and observed the same behavior on SU and SO. Additionally, on SO and meta I have the same problem with Ignored Tags. I did not try this with Ignored Tags on SU, but I have never had an ignored tag on SU, and do not see the blank box. On SF, I have never had an Interesting or Ignored tag and do not see the empty boxes. I have seen the behavior described above using both Chrome 18.104.22.168 and 22.214.171.124 and IE 8.0.6001.18702.