I had a similar problem at startup with an unwanted installation program trying to run. What I had to do was Ctrl-Alt-Del as soon as the program started running, go to Task Manager, and then End Task. Having done that, I went to Run > Msconfig, and unticked the rogue software from the Startup list.
That did it for me, but I can't guarantee it will stop it trying to run at the other times you mention. But maybe you'll then be able to uninstall it if you've got it out of the Startup list.