Hi, lately my Pc has been acting slow. I want to defrag my computer like i normally do, but everytime i have tried for the past month it just keeps restarting defraging so after 18 hours and its gotten to 80% i get pretty mad, Same happens with scan disk, IS there a way i can do this not in windows but in dos? I'm, pretty sure there is

Also i think i might have a virus but not sure, i used my mcaffe virus scan which is updated to the latest, it picked up nothing, and i did housetrend's online virus scan which picked up nothing, but at times my comp freezes, random errors come up, and the begenning dos startup has changed

Oh i really don't want to format my drive