please test this  may be need system ram up to 4gb

yacminer --scrypt-chacha --worksize 128 -g 1 --lookup-gap 6 --buffer-size 1648 -R 4736 -o stratum+tcp://: -u -p --nfmin 4 --nfmax 30 --starttime 1389028879



or


yacminer --scrypt-chacha --worksize 128 -g 2 --lookup-gap 6 --buffer-size 824 -R 2368 -o stratum+tcp://: -u -p --nfmin 4 --nfmax 30 --starttime 1389028879

if not solved go to http://www.ultracoin.net/configgen_raw.html select your card  select N factor 13 and click calculate and replace --starttime 1389028879