in around last 8-10 hours my reject rate has been 7%...is this normal...always on middlecoin.com i have these days when rejects are huge and I am forced to hop here and there:(
On the second miner rig its 9%

Check which server you are on; make sure to select the middlecoin server geographically closest to you.
Then I would check your mining configuration. I have high reject rates before with an incorrectly configured cgminer.conf
I use middlecoin.com because other servers become down now and then. Although the closest to my location would be asia server.
My config on a 5870 is as follows:
timeout /t 60
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer --scrypt -o stratum+tcp://middlecoin.com:3333 -u 17fZoMHnQ4or5GhrwXznRZ52jPE3pqjmwM -p 1 --thread-concurrency 7168 --lookup-gap 2 -I 19 -g 1 -w 256 --temp-cutoff 95 --temp-overheat 80 --temp-target 70
On a 7950 it's:
#!/bin/sh
export DISPLAY=:0
export GPU_MAX_ALLOC_PERCENT=100
export GPU_USE_SYNC_OBJECTS=1
cd /home/deltree/Desktop/miner/cgminer-3.7.2-x86_64-built
./cgminer --scrypt -o stratum+tcp://eac.poolerino.com:3334 -u x -p x -I 19 -w 256 -g 1 --gpu-engine 1100 --gpu-fan 50-100 --gpu-memclock 1520 --gpu-powertune 20 --temp-cutoff 95 --temp-overheat 80 --temp-target 70
Removed thread concurrency yesterday but it hasn't done anything really, dont use the conf file only bat file. No HW errors on any, using cgminer 3.7.2 hash rates are 400 and 643 respectively.