It might have been with a program you installed, and it can usually come from anything illegal you may be doing (obviously this is not the place to discuss this).
If you can't try to reinstall your software as a whole using a disk, I know there's an option to restore your computer to the beginning (usually called something like "system default"). See if you can do the disk, first, and then you can tell us the software information to help us out a bit more.
Avatar: In memory of ieatwyverns <3
Thank you, Vasco <3