If you start up Mac OS X in single-user mode or verbose mode, you may see some messages that look like this:
Feb 15 17:22:09 localhost mach_kernel: kmod_destroy: com.apple.iokit.AudioDeviceTreeUpdater (id 16), deallocating 3 pages starting at 0x7204000
You may safely ignore these messages.
These messages only indicate that drivers are being unloaded to conserve memory when the devices they support are not found. These messages may also appear in the file /private/var/log/system.log.
If you are using the log to gather information about another issue, look for the lines just before or just after this text, starting from the last line of text and reading backwards several lines.