1. > Open Norton.
2. > Click 'Settings'
3. > Scroll down to 'SONAR PROTECTION'
4. > Click 'OFF' (The Bar that says 'ON')
5. > Click 'APPLY'
6. > Set the duration for 15 minutes.
7. > Run WoW and begin downloading.
*Note: These steps do give you a risk of being vulnerable for 15 minutes. If you are unaware, you are only applying 'Sonar Protection' off for a guaranteed 15 minutes. You can turn it back on manually after you have downloaded the patch. Also, please, refrain the nasty comments on another post. Thanks! I hope this helped.
-Other Solution- (Recommended by Players & Blizzard)
1. > Press 'Start' on the bottom left hand of your desktop.
2. > Go to 'My Computer' or 'Computer'
3. > Go to 'Local Disk' or 'OS C:'
4. > Go to 'Program Files' or 'Program Files x86' (Where ever is your WoW Folder)
5. > Go to 'World of Warcraft'
6. > Repair World of Warcraft (Repair.Exe)