This should be telling you it isn't the modpacks that are the problem.
Wow. You don't have any clue yet you talk like having some.
I copied the packs to other harddisks to make sure it's not a hardware problem.
I even scanned all harddisks for problems more than twice - i can rule out those.
I changed the loader to multiMC so i could install a different forge version, i changed other mods
to higher versions, too. I even updated the LWJGL to the 2.9.3 version.
I spend hours of recovering lost saves or doing backups from gameworlds, reading log files
so don't give me that "this should be telling you bullshit" ! Seriously!