You might be able to make one yourself (a simple program running at startup appending something to a logfile of your choice) but if you can make it anybody else logging in with your account can undo it.
Why not change the password?
I have windows installed in my desktop. I have heard that there is a way to find out if other people has logged on to your computer in your absence by checking the log. Can anyone tell me how this is done. I am the administrator and my account is passwrord protected but it is known to two more people. my computer is not connected to LAN. Can anyone help me by telling, how you check the log???????