Been awhile since I played MC, but back then Java8 was causing all kinds of issues. Didn't load Java7 initially 'cause I didn't feel like adding yet another spam donor to my email addy [you're required to register with Oracle to download anything from the Java Archive].
Aside: Meteors keep wrecking my base wall, so I looked in the configs to see if I could disable block destruction...turns out it's already disabled?
From Galacticraft core.conf, lines 183 + 184
Set to false to stop meteors from breaking blocks on contact.
B:"Meteor Block Damage Enabled"=false
I know about the Shield / Obsidian Glass but I'm nowhere near setup to produce those in the quantities I'd need.