Download the full SP2 package to your computer from the link below and then install it.. (It's a large file, about 266 MB, so make sure you have a broadband connection.) If you can't download the file to your computer, then find a friend or family member with broadband and a CD burner, then download and burn it to CD, then transfer it to your machine.

If "Chkdsk" found problems, it's also possible that your hardrive is headed south.. Be sure to make backups NOW.

Hope this helps.