I wanted to replace a light switch as I have done many times before. It is contained in a 4-switch setup like so:
[3 way switch on circuit 1][3way switch on circuit 1][3 way switch on circuit 2][2 way switch on circuit 2].
I was replacing the farthest to the right: the 2 way switch on circuit 2. I turned off both circuit 1 and 2 at the breaker. I replaced the switch and turned the circuits back on. The new switch worked, but circuit 1 tripped!
When I try to reset circuit 1, it immediately trips again.
I have posted some pictures of the wiring here: electrical problem - Imgur. Again, I didn't actually make any changes to the circuit that doesn't work, so is there anything that i might've done accidentally when removing/putting the back the switches into the box?

 

No 2-way switches in the U.S. That's what the British call a 3-way.. Do you mean the dimmer on the right? By different circuit do you mean different breaker? The dimmer's power seems to come in at the switch box not the light. Is that correct? If so where are the two whites that are associated with that circuit? They should be connected only to each other.

 

Does the breaker stay on with the switches out of the wall?