In my version of ubuntu (12.04) bootchart creates a different log file every time the computer boots, this goes into the directory /var/log/bootstrap. Though, bootstartgui looks by default to the file /var/log/bootchart.tgz which does not exist.
In 12.04, if you install bootchart properly, you automatically get an image file of the boot graph representation, so you do not need to run bootstartgui.
In fact, it is enough to run (Alt+F2):
nautilus /var/log/bootchart
then double click on the image that contains the date and time that you are interested in.
If you want to delete useless logs and save space, you can start nautilus with sudo from the commandline: Type (Alt+Ctrl+T) and then:
gksu nautilus /var/log/bootchart
This will give you a window where you can also delete files. Be very cautious not to delete anything on another folder!
Please use pybootchartgui (available in Software Centre). It'd create a graphical log after each boot.
Checking dmesg output would be equally good, but less 'visual'.
Please disable from Startup Application whatever you don't need, and make sure that the HDD is the 1st boot device in the BIOS.
Best Answer
Stopping
Re-starting
or:
makes it manual.