With this bat file I don`t have any HW errors or rejects

setx GPU_FORCE_64BIT_PTR 1
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
del *.bin
ultracoinminer --scrypt-jane -o stratum+tcp://**** -u **** -p **** -I 12 -g 2 -w 256 --thread-concurrency 16384 --lookup-gap 3 --gpu-engine 1000 --gpu-memclock 1250 --gpu-vddc 1.150 --gpu-powertune 20 --gpu-fan 50-100 --temp-cutoff 80 --temp-target 67 --sj-nfmin 4 --sj-nfmax 30 --sj-time 1388361600 --failover-only --no-submit-stale

I use this miner : h t t p : // tinyurl . com /qgak7dg and I get 108 KH/s.

This is not very fast but this is the only way I can mine without HW errors and rejects.