Windows will usually tell you when you've run out of space or are running low or your machine will be running really really slowly. Just a little housekeeping is required to help solve this problem, here are a few things you can try:

  • Empty recycle bin
  • Check downloads folder and delete anything not needed then empty recycle bin again.
  • Delete any documents not required that have been saved on your Desktop or My Documents folder. Empty recycle bin. 
  • Files that you wish to keep but don't use often, consider backing them up to a CDR/DVDR, external hard drive or USB stick.
  • Perform a disk cleanup - in your file explorer, right click on your C: drive then select properties, and then Disk Cleanup (see screenshot below) - you'll be presented with a report of 'rubbish' that is usually safe to get rid of.