Somebody know why my server was crashed after:

Code:
2011-05-05 14:26:30.271124|INFO    |VirtualServer |  1| query client connected 'Unknown from ***.***.**.**:52706'(id:1966)
2011-05-05 14:26:30.275573|CRITICAL|StringHelp    |   | Assertion "unicodeCharacterNumber >= 0x80" failed at common/custom_string_helpers.cpp:567;