Steps to reproduce:
1. mongod --install --logpath c:\data\logs --logappend
2. net start MongoDB
3. at this point mongod is running as a Windows service
Upon reboot mongod repeatedly fails to start. If you watch its status using the Windows Services Administrative Tool you can see the status alternating between Starting and Started.
Each time mongod attempts to start it writes a few lines to the log file, and the attempts to start are happening in such quick succession that the log file is growing at the rate of several MB/minute, so unless action is taken the disk can be filled up.
To break out of the cycle repeatedly run:
net stop MongoDB
The problem is that this command only works when the service is in the Started state, which it is only very briefly before failing. So you have to keep running this command until you get lucky.
The other piece of information is that upon reboot the mongod.lock file is not empty. It contains one line of text with a number in it.
The two log files attached are the log file right after the service was started for the first time, and the first 20K of the ever growing log file after reboot.