unexpected shut

Please help guys. whether it was missed or ignored yesterday I don't know.
Im experiencing enexpecyed shutdowns and today the OS would not Boot.

this is a 64bit Win 7 retail OS

Please help

thank you

Matt

Update your Realtek 10/100 X64 Driver ,Rtnic64.sys
Realtek

Code:

BugCheck 9F, {3, fffffa8003cc3a20, fffff80000b9c4d8, fffffa80067d4240}

*** WARNING: Unable to verify timestamp for Rtnic64.sys
*** ERROR: Module load completed but symbols could not be loaded for Rtnic64.sys
Probably caused by : Rtnic64.sys

Thanks again,would be stuck without real experts