This is a really weird one so don't know if anyone else has seen this but any help gratefully received.
We are running on EE 1.10 and have just added a load of new products. When we use the quick search for a product it shows up but if we try to add to the basket it sometimes fails to add then 404's and the product will not show up in the search results again. The 404 only seems to be when there is a single search result and when there are multiple results the page refreshes to the search results but the product we have just added is removed from the search results. Inventory is fine so the product is in stock etc.
We've had to remove the add to basket action from the list.phtml template for the time being but obviously want to be able to reinstate it but can't while this is continuing.
My local dev version of the site was doing this so I cleared out the search tables and rebuilt the full text index (this occurs with both like and combine searches)