When Big Reactors was in FTB Monster 1.0.1 my Development Log filled with Open GL Invalid Operation (1282) errors while running on an AMD based laptop.

Toggling Minecrafts usual settings (Graphics Fancy/Fast, OpenGL advanced vs normal) made no change. This is the vanilla renderer not optifine.

Anyhow, differential diagnosis eventially had it that removing Big Reactors was key to solving the errors - which were slowing rendering and causing the client to disconnect.

There was no actual Big Reactors content placed in the world so I don't know why.

That's bizarre. Which version of BR were you running? In either case, without any BR content placed in the world, none of my custom rendering code would've been active in the first place.

I've found this, which may be related. Are you using screen-recording software?

http://playclaw.com/forum/index.php?/topic/3201-playclaw-causing-opengl-errors-with-minecraft/

Adding to that I found this in my log http://pastebin.com/RSy8Z3qu

complete log http://puu.sh/6yHbS.2 for X9 version. I think it has to do with the worldgen of Yellorite, cause that mentioned area is unhabitated and almost freshly generated chunks. Client crashed when I tried to search for it

That would be strange, as yellorite has its own block ID and uses metadata 0.

I'm betting some other mod is placing blocks with the same ID as you have set for BR small machines. Can you go over your configs?

You definitely have at least one conflict already:

2014-01-26 12:40:45 [INFORMATION] [STDOUT] CONFLICT @ 6819 item slot already occupied by openblocks.common.item.ItemOBGenericUnstackable@6f5b8f0f while adding openblocks.common.item.ItemStencil@bcff8c5

Alternately, try changing the BR small machine ID in the config to a different ID that's not in use.

Closing this - thatsIch's problem was due to BR inheriting a blockID from a removed mod, which had added large amounts of that blockID with different metadata values as worldgen.

Just wanted to say, that they may or may not be related to each other. cause I still get this error. My error log is now at ~18mb :D

2014-01-26 16:49:48 [SCHWERWIEGEND] [Minecraft-Client] ########## GL ERROR ##########
2014-01-26 16:49:48 [SCHWERWIEGEND] [Minecraft-Client] @ Post render

but the "good" message is, that I removed BR and I still get this, but I am not sure what caused this problem now >_>