When logged on (Firefox or Chrome) my Search box is replaced by the Alerts icon. I view the site at 160% but even reducing it to 70% doesn't reveal the Search box.I don't think there are any other reports of this, but that does not mean that there wont be. I have had similar problems on other websites before and used the zoom out function in my browser.
I've no doubt it will be solved though.
Clicking the Forums tab brings up a 'Quick search' box immediately above the page numbers. It's quite difficult to see because it's very low contrast.