Savantster

You might want to explain that it was just fixed, 2 days ago.. and the version that's needed instead of saying "latest" since that's not "recommended" and people may think you mean the -doesn't work with 1.8_20- version, instead of the newly fixed version. So.. if you're running Java 1.8_20, you need Forge version 10.13.1.1217 which was just fixed for 1.8_20 on the 14th.

You have to make sure you remove -all- your 1.7.2 mods when you switch to 1.7.10.. not all mods for one will work in the other. Let us know what that does..

I've always gotten errors with the win installers.. get the .jar installer and see if that does it..

Make sure you uninstall ALL java 1.8 versions, then REinstall your java 1.7.. I had lingering binaries somehow and needed to reinstall 1.7 to clear the bad binaries..

The installer for forge should be run from some temporary place, not any place you plan on having the final system installed to.. Though, it should also be putting out files with a different name than the installer, so technically it "shouldn't" matter.. but.. So, have you actually logged into your 1.6.4 -world-? For the installer to work, you have to have launched the 1.6.4 profile at least once.. past just logging in, and into the screen where you can pick a single player world to run. That initial running is what downloads all the game pieces for that version, and Forge needs those pieces already there to install. And I've found that the .exe installers don't always work nice, the .jar is the way to go... Also, if you already have a forge installed (for the 1.6.4), it might not try to install again.. have you tried creating a new profile and seeing if you have access to a Forge for 1.6.4 as a profile/game?

I ran into a problem with Java 1.8_20 not being able to do Minecraft.. I recommend uninstalling 1.8 of Java and making sure to reinstall 1.7_65 (or whatever).. I still had a lingering Java.exe somehow, after uninstalling .. and had to reinstall the 1.7 stuffs..