My modpack keeps crashing back to launcher

[IcyIsAToast]

Whenever i try to open any modpack except for vanilla, after a few seconds the modpack crashes back into the launcher. I tried looking at some posts about this but nothing helped. This started happening after i got a faster processor so I assume it's a problem within my specs. I would just like to know if that is true or not, and if it isn't if there is a way to fix this. If there is not it doesn't matter that much cause i can play modpacks on my laptop it's just a fair bit slower

Update: I tried reinstalling the pack to a custom (reccomended) version and some magic happened, it worked! BUT There's another problem: when minecraft loads up this popup appears: Forge Mod Loader has found a problem with your minecraft installation The meds and versions listed below could not be found ForgeMultipart : any The file logs/fml-client-latest.log contains more information. I tried to find this file but i can not seem to find it. For context i'm trying to launch Steve's Galaxy (1.7.10)