Chrome here. There must have been a very recent change to the forum software... a couple of days ago, I clicked on search and moved the cursor and clicked on advanced search, and it let me enter the keywords and the search was performed. Now when I click on search, if I move the cursor (to try to click on advanced search), the drop-down disappears, but if I just start typing, it accepts the input. However, as others have noted, basic search is pretty useless - I always use advanced.
The good news is that the menu bar now has advanced search on it, just to the left of search; it points to the link that Rich provided and it appears to work just fine.
Speaking as a former IT developer and project manager, I scream whenever I see changes being implemented that have not been fully tested. And web software should not be developed in a way that is browser-dependent. Maybe my dislike for these poor practices is why I retired early.
Edit: Rich made his post above while I was typing my rant. Now there's one search option on the menu bar, and it seems to work. However, the customer (in this case, OGR/Rich) shouldn't have to be the one to fix that kind of thing.