Lately I noticed wired stuff in my computer like files disappearing, a restart without a reason no warning or notification just restarted suddenly, so I thought maybe someone is assessing my computer remotely than I checked the event log it haven't been logged the file disappearence and the restart, also when I opened the task manager the cpu usage is high after 1 second at most the usage drops and the application list change, so how do I make sure that my computer is being accessed remotely and how I prevent it from happening again and if is possible I want to know who is accessing it.
Note I have kaspersky installed but before I install it I used the computer With out anti virus.