System log question


My Mac seems to be running normally. However I notice in the system log hundreds of entries like:

Sep 30 08:59:59 nealnt.local UserEventAgent[181]: Could not get event name for stream/token: 0x3: No such process

Sep 30 08:27:11 nealnt kernel[0]: Sandbox: sandboxd(54321) deny mach-lookup

Sep 30 02:00:16 nealnt.local sandboxd[52316] ([7422]): Mail(7422) deny file-read-data /Library/Preferences/

Probably there is no cause for concern. But they probably occupy cpu time. Also it makes using the system log as a troubleshooting tool very difficult.

Any comments on this?

Mac Pro, OS X Mountain Lion (10.8.2)