Prob 2 is a probe error. This means the logger took reading without the probe being inserted, or the probe is no longer detected in the logger, meaning the probe is possibly broken. Similarly, it can say Prob A, if it's using an "A" type probe.
The three dashes indicates the logger has been stopped; whether that be from removing the battery at some point, or the logger glitched and reset itself, this does not mean the battery is dead. This just indicates the logger needs to be set up again with the EasyLog software.
There are two possible reasons the logger can't be detected by the computer:
The first being that every time it connects it has a power surge of sorts and restarts the logger in the middle of the connection. If you watch the lights on the front while you plug it in, they will blink rapidly when you connect the logger. If this happens, remove the battery and bend a paperclip to where you can touch both ends to each terminal end of the battery for about 5 seconds. (this will not shock you)
If that is not the case, the usb driver on the computer is not working correctly. Please follow these instructions (CLICK HERE)
There is a known issue with the logger taking a bad reading and the screen not coming back on. A workaround for this is to keep the screen always on, which is in the initial setup. (this will not drain the battery as quickly as you may think)
The logger may ready -50 on the graph, or say Prob2 on the screen or just show a blank screen with the red light flashing. Most likely the logger is set to immediately start when the program is finished running the setup. We always recommend you choose the option to have the logger start when the button is pressed.
This is actually "PS" for "push to start". This means you have correctly set the logger to start when the button is pressed and it's just waiting for your input.
This is actually not an error, this is just saying "Log" as in, the logger has started logging readings because you pressed the button.