[Error in launching the game]

So, I'm pretty sure this is where this would go. It being a problem with Forge is the only thing I can think of. 

Every time I try to launch the game when I use Forge, I get a "Launching the game failed!" error.

The full error log:
 

Failed to download file, the file contents differ from what was expected.
Name: jopt-simple-4.6.jar
URL: https://libraries.minecraft.net/net/sf/jopt-simple/jopt-simple/4.6/jopt-simple-4.6.jar
Filename on disk: jopt-simple-4.6.jar
Path: C:\Users\Riptide\Twitch\Minecraft\Install\libraries\net\sf\jopt-simple\jopt-simple\4.6\jopt-simple-4.6.jar
Exists: File

 

I'm really sorry if this isn't a forge issue, but it only happens with forge regardless of what mods I use so I figured I'd check here!