|Type msconfig in the Run box and hit the Enter key. Look in the Startup tab and see if it is listed. If so you can untick it there. When Windows starts, tick the box to ask it to stop telling you that you are in diagnostic mode. |
If there is some better way at stopping it (from the program itself) then do so but the above will not cause any issues.
You said "it doesn't appear in the startup menu". If you mean start > All Programs > Startup, then few programs run from there. Most start from the registry.
How to know you are getting old 5:
A lamp post backs into you