Hi,
If you use two (common) search parameters, show results as messages, and specify certain boards to search, several pages of results will be returned. However, subsequent result pages (beyond the first) will indicate that there are no results.
This behaviour does not occur when a single search parameter is chosen. I've not tested for other conditions that trigger this bug. The problem may be more general.
This has been reported before and is a known bug with 2.0 RC3 and is related to multiple terms not being handled correctly.
Seems similar to: http://www.simplemachines.org/community/index.php?topic=371048.0
(and other topics).
Thank you for your report.