These issues are currently known to us and are being resolved. If you are aware of other issues not on this list, please notify firstname.lastname@example.org.
The search parse sometimes gets confused with dates in certain formats. For example, the year 1998 can be read as the 19th of the current month in 1998. It's generally best to use whole dates, like “5 Sep 2007” or at least month/year combos like “Sep 2007”. A re-write of the date parser is pretty high on the list!