eBay seems to have shifted to a new search engine. I've had problems with it. Many others are complaining. Look here, for example, to read the complaints:
http://forums.ebay.com/db1/forum.jspa?forumID=80

However, this "secret" page will bring you to the old search engine. It worked for me.
First, click this link: http://shop.ebay.com/

Then, hit the "opt out" link in this sentence on that page: "You are currently testing eBay's new search experience. If you prefer, you can opt out of the test."

Robert