BootLog

If you need to know how many times a day you reboot your computer, or how often your Windows crashes, download BootLog. The program will make a log file when Windows boots and exits properly. If Windows crashes, the logging is not done, and BootLog will determine that Windows was terminated incorrectly accordingly.

BootLog can create graphical diagrams based on the log file, but to do so you need this log file viewer: http://www.stefanlautenbach.de/download/bootlogv.zip

To install the program, unzip it into the directory with the BootLog View viewer and type BootLog.exe -install at the command prompt. This will write the program to the registry and start it automatically.