Download is only when you copy a file from a remote source to your PC. you don't "download" files from disks, or "download" installers from them- that's simply a copy operation; a disc in your CD drive can hardly be called a "remote" source.
From the sounds of things you either have malware infecting the Drives upper/lower filters, or the drive is shot.
First try the
Missing CD patch.
Go to Device Manager(Start->Run, "Devmgmt.msc"), click a "+" sign next to IDE ATA/ATAPI Controllers.
You'll see two items:
- ATA Channel0 (or Primary Channel)
- ATA Channel1 (or Secondary Channel)
Right click on each of them, and click Uninstall. Confirm.
Restart Windows. They'll be automatically reinstalled.
IF that doesn't fix it, try running "sfc /scannow".