How To Tell That Your Computer Has A Virus

Question

How can i tell if i have a virus on my computer?
i was going to a website then it said that i have a virus. When exited the program it went away. So how can i tell if i have a virus on my computer?

Answer:

If you notice your computer behaing strangely, for instance some strange programs are running, some of your programs cannot run, your files are corrupted, you get new files from nowhere, etc. These are some of the signs that your computer is infected.