I have the same problem and looking for a solution I ran into:
http://forums.macrumors.com/showthread.php?t=1746000
which suggests to rune:
softwareupdate --install --all
which I attempted but got:
Finding available software
Feb 2 10:25:16 Armandos-MacBook-Pro-2.local softwareupdate CLI[1504] <Error>: /usr/sbin/softwareupdate: Service connection interrupted!
Feb 2 10:25:16 Armandos-MacBook-Pro-2.local softwareupdate CLI[1504] <Error>: /usr/sbin/softwareupdate: XPC error in __45-[SUCommandLineTool _refreshAvailableUpdates]_block_invoke (Error Domain=NSCocoaErrorDomain Code=4097 "Couldn’t communicate with a helper application." (connection to service named com.apple.softwareupdated) UserInfo=0x7f925a407300 {NSDebugDescription=connection to service named com.apple.softwareupdated})
I am not sure what to do next but I figured I post it here as I see I am not the only person having this problem