OK, then you need to be checking the computer for viruses, malware and any bad recently added programs first.
Should none of these turn up anything, next you would go to "Start" and then in the search bar type "msconfig" (without the quotes).
NOTE: Be extremely careful while in here. Way to many people will just start changing things, deactivating things, removing things, etc., and do way more damage to the computer than they actually started with. So do not change anything without being absolutely sure what it is you are changing.
In msconfig you want to go to the "Startup" tab and check what is set to auto run when you turn on the computer.
After any changes you make in there, once saved, then reboot (turn off and back on) the computer.