I built a windmill-"tower" pretty high in the air and everything was running VEEERY fast... but then it decreased over the time. I thought maybe it has something to do with wind, varying from day to day, but when i came up to them to destroy them, most of them were plain generators instead of windmills. I am 100% sure that i placed windmills (there were too much generators anyway, i couldn't be such a noob). I looked at them with lockblock, no block placement or destroying (they showed that i placed ID248, all of them). I will try to put them below 127 next time, maybe it has something to do with that. It sucks that i lost like 4 stacks of iron but **** it, mining will safe the day.
I think there is a bug with windmills if they're placed above height level 128 or something but i can't remember it, are you sure you used a wrench when destroying them or did you destroy them with a normal pick/drill?
Oh you didn't destroy them?, thats odd you sure it wasn't just a visual bug. Not regarding the windmills there is something with ids and using W/E so idk if someone id a W/E or not if they didn;t it must have been a very strange bug.
Pretty Sure that Windmills are designed to be unreliable and occasionally 'explode'back into generators if put above a certain height (higher they are, the more power generated, but also more risky to 'explode'). EDIT: "- If a wind mill produces more than 5 EU/t, it has a chance of breaking. If a wind mill's effective height is no more than 80, it cannot break." - IC2 Wiki
