I had a similar problem when I updated to 10.11.5, except that instead of halting or freezing entirely, the message "lsd quit unexpectedly" (lsd presumably being an acronym for Launch Services Daemon) appeared repeatedly after being dismissed, and the system became so sluggish that it couldn't be used. Safe boot didn't fix that either, but I was able to fix it by deleting the contents of /var/folders. I probably could have determined a more precise cause, but a quick search didn't reveal anything, so I discovered the remedy by performing some basic recovery steps. I don't like deleting the contents of /var/folders, but for me, the only serious data loss caused by doing so is that the Launchpad items get reset. But a quick recovery for that is to navigate to the current temp folder, which can be managed by the AppleScript below, and find the temp folder on a backup, drag the three live Launchpad database items to the trash and copy the backed up versions to the current Launchpad database folder, then log out and back in. Launch Services may also need to be rebuilt using a maintenance app such as Onyx.
set this_user to do shell script "id -un" as string
set i to POSIX file (do shell script "echo $TMPDIR")
set any_target to "db"
tell application "Finder"
set r2 to get container of folder i as alias as string
set f to get container of folder i as alias as string
reveal f & "0:com.apple.dock.launchpad:db:db"
try
activate
update
end try
end tell
