There are always going to be oddities with any big online service, but this one seems to be persisting. Join the discussion in trying to figure out a pattern. For maybe a week, Google has been returning zero results or "1-1 of about xxx,000" for common searches. One-word searches seem unaffected, but there are certain two-word combinations of common words like candle truck or speaker bracelet. Reversing the order can affect searches too: motorcycle candles vs. candles motorcycle. The strange thing is that usually the 1 or 2 results found are to commerce sites. Read the Search Basics, compare your notes to GoogleWhack's, have fun looking for patterns, but remember that Google always returns slightly different results for different IP numbers.
(Update: 13:56 GMT by J : When I first posted this story it said the problems have been occurring "for several weeks at least" -- but it seems to be more like one week.)