Over the last two days there have been massive DDOS attacks on several pools.  Thus, you may not have been mining the entire 12 hours.

That's why I use 1gh as my main pool, with failover to dwarfpool if 1gh goes down.  Dwarfpool's US server, moria, seems to be down more than its French server, erebor, so even though I'm in the western US I use erebor.  Like this (I'm running Linux):

#!/bin/bash
# /usr/bin/run_cgminer, to restart cgminer if it segfaults
# to run: start a terminal window, then enter rxvt -e /usr/bin/run_cgminer
# to halt: Ctrl-C the run_cgminer window, then Ctrl-C the main terminal window within the 5 seconds before run_cgminer restarts.

export DISPLAY=:0
export GPU_MAX_ALLOC_PERCENT 100
export GPU_USE_SYNC_OBJECTS 1

while [ true ]; do

/mnt/sda1/Downloads/MAXCOIN/cgminer-3.7.2/cgminer_keccak-master/cgminer --no-submit-stale --keccak -o stratum+tcp://maxpool.1gh.com:17333 -u mS47ysKD6Zh14v2N6dZPqBXDNL3JYFQ9kV -p x --failover-only -o "stratum+tcp://erebor.dwarfpool.com:3339" -u mS47ysKD6Zh14v2N6dZPqBXDNL3JYFQ9kV -p 1 -I 13 --auto-fan --temp-target 75

sleep 5

done

Also, be sure to use the version of cgminer 3.7.2 available from 1gh (it compiles as 3.7.3).  It gives a 10-15% boost in MH/s over the earlier 3.3.6 version.  And on my Linux, I had to use Catalyst 14 beta (13.35), not 13.1, to get the 290X to run at full speed.

Here's what the run_cgminer window looks like.  At the moment, 1gh is down due to DDOS attack, so I'm mining on erebor (dwarfpool):

http://i57.tinypic.com/b6d0ki.png