Question: BlockIDs

I am having the same issue. I did test a little bit, did a fresh install with all the normal crap, but using the first version of the 1.2.3 forge, and got some weird error, then i upgraded forge and ic2 worked as expected. With the first version of forge it failed to generate the block and item id's. And of course once i upgraded forge, it all worked. So i then went back to my main MC 1.2.3 build, removed ic2 because it wouldn't work, then upgraded forge from whatever it was to 1.4.0.57, started MC, ran fine, then went ahead and added ic2, started MC, crashed as expected because i know the id's will conflict, which is actually what the error report stated, so i go into config and of course no id's have been generated so therefor cannot be changed. I am a little stumped as to what to do. I tried running error bat as well to see if that would generate and no go, i also tried simply copy/paste the whole config when i get it to work with no other mods. No go.

Might have a quick fix...

If your having the same issue as me, look at the error report and whatever mod is conflicting with ic2, go into the modloader config and disable whatever mod is conflicting. In my case, first was tf2, so i disabled, second run it conflicted with twilight forest so i disabled TF, third it conflicted with redpower, before disabling redpower, i checked the config again and it finally generated all the id's. So now, go into the config, adjust all your id's and you should be good to go. Don't forget to reenable your disabled mods. I just tested this and i now have ic2 running woot