It's an issue with the board. IPB staff is working on it.
I'll try to manually unarchive them now, but in the past it has destroyed some active threads so have been hesitant to do this manually until a fix has been tested. That's what happened to the CVPS / SolusVM exploit thread though I think we're close to having that fixed.
Sorry about this, I know it's an inconvenience. Some great tutorials in there.