Have experienced that bug a couple of times too. Just go into your texture packs option menu and then click done. The texture pack should reload and everything should be fine. At least it worked for me. Don't know about the windmills though... Maybe you put them too close together?
You should use Insulated Copper Cables in the recipe, not gold ones. This can also be seen on the wiki Gold ones are used to export power from the MFE, since the EU packets are too large for copper.