TechNetTech,
The CMOS checksum can give a false positive if the BIOS says a particular region is writable but really is not. We write a value to that address, the read the static value and interpret it as a failure. It would not affect the operation of the system so can be safely ignored.
I am a member of the camp that it is is better to leave systems on. When a computer starts up, all the components in it expand at different rates. This creates stress on the solder joints and connections. Once operating temperature is reached this process stops and homeostasis is reached. It you then turn the system off the process begins again, in reverse.
In my experience the electrical components far outlast their physical connections to the real world, surface mount chips and RoHS compliant systems with no lead solder doesn't help the situation.
-Fred