Laucher on USB stopped loading Forge 1.7.10

I´ve got my Minecraft on a USB-Stick, but that isn´t the Problem (it actually works, by redirecting %APPDATA% to a custom directory).
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It was the first time i lauched my Minecraft with Forge for Minecraft 1.7.10 - The Laucher loaded but suddenly, i got a FATAL ERROR in the Minecraft Laucher Info. I copied everything into a text-file. This is what it says:
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[read the attachment]
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it told me to report this bug, so i did so.
Maybe i did something wrong configurating forge for my USB-Minecraft, or its a bug in Forge or its a bug in the Launcher.
Either way, i hope, i can soon play Minecraft modded on my USB-Stick