The KB will sometimes fail to return any results. Here are some possible causes:

The phrase "100% cpu" will fail. Use "high cpu" instead. This is a bug in the user interface code which we should have resolved shortly. Other queries with characters that must be html-escaped for processing (such as ; ? & %) may also fail.
A search engine may be down. We have redundent search engines, but they are not fully high availability at this time. We are working to improve that. In the meantime, trying the search after a few minutes delay should show results.

We hope to have all of these issues resolved shortly.

regards,

KB Team