There are several reports of a bug with Google Image search starting back last week that have gone unanswered in the Google Web Search Help forums.
It seems that this is impacting Windows 7 users who are trying to click on images within Google Image search. When they click on an image, it snaps them back to the top of the page, instead of opening the image in a new window.
The first report was on January 7th:
Using Google Images - When I click on an image, instead of opening up the image in a new window like it used to, the page simply returns to the top of the page. And also the hovering tool no longer works. I have gone into settings and tried clicking & unclicking (can't remember the exact words) 'open-image-in-new-browser-window' but nothing changes. I hope someone can help.
The reports still keep coming in, even as of this morning.
Google has yet to confirm or acknowledge the bug, but several users are reporting the issue and the pattern seems to be Windows Vista, Windows 7 and Windows 8.1 using IE10 and IE11.
Forum discussion at Google Web Search Help.