My computer is now really slow for some reason

The other night I turned my computer off, but accidently turned it back on again, so I turned it off by pressing the off button in the back as I was tired and wanted to sleep. I woke up and turned on my computer, and it took a while to log me in, the computer was trying to restore something, I cant quite remember what it was. After that had finished, my mouse cursor has been very slow, and everytime I open my browser or skype, it keeps telling me to close the applications because its slowing down my computer, this has never happened before, does anyone know if there's anything I can do to solve this ?