Tried to open the gui.
But it crashed.
http://paste.ee/p/5trTm

You mean the circuit database?
Because the circuit database crashes for me but the Circuit Table works fine.

Datebase, sorry

Then please rename it.

I can't reproduce it. It's very likely that another mod is conflicting here, but I don't see any reason why a mod would set the 'mc' field in GuiContainer to null... (sorry for the in-depth talk here :P)

EDITED! When SIMPLY right click the block (Curcuit Database) is NOT open GUI. When SHIFT-RIGHT click the Curc.Data. is crash!!!!

This is the crash log: (My modpack is Bevo Tech Pack Update7!!!)
http://pastebin.com/LNef1m9J

Reopened because apparently some other people still have it.

I'll try to pin down a culprit mod.

I was able to reproduce it running only BluePower 708 - no other mods. The complete logs are more helpful than the crash report - among what they say:

java.lang.NoClassDefFoundError: scala/actors/threadpool/Arrays
at com.bluepowermod.client.gui.widget.WidgetTab.(WidgetTab.java:24) ~[WidgetTab.class:?]
at com.bluepowermod.client.gui.GuiCircuitDatabaseMain$1.(GuiCircuitDatabaseMain.java:47) ~[GuiCircuitDatabaseMain$1.class:?]
at com.bluepowermod.client.gui.GuiCircuitDatabaseMain.func_73866_w_(GuiCircuitDatabaseMain.java:47)

It looks like Scala's Actor API isn't there at runtime - it wasn't in my libs or libraries folder. You might want to include it in the download or retrieve it with DepLoader, since it doesn't look like Forge includes it automatically.

I can reproduce it, when I'm using a non-dev build. Turns out, I'm a derp ;). Fix coming up

Work-around until a new build comes out:

Download ScalaActors from http://www.mediafire.com/download/0xh3o3v2bjt3sak/scala-actors-2.11.0.jar and put it in your mods folder.

If you don't trust me, download all of Scala from www.scala-lang.org and put lib/scala-actors-(version).jar in your mods folder.