Only for some terms that we have discovered (eg "backpack", etc., for other terms everything is fine) our Magento store search seems to time out after about 10s and returns a blank page saying:
"Service Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later. Additionally, a 503 Service Unavailable error was encountered while trying to use an ErrorDocument to handle the request."
What could explain such a selective and weird behavior and how could I avoid it?
I already tried modifying the configuration parameters in System > Configuration > Catalog > Catalog Search. I tried the 3 types of search (Like, Fulltext, Combine) and tested permitting layered navigation for any number of results, but nothing helped...