any idea, please?
No , but change your pool (look the efficiency)
go here :
http://xbit.nonce-pool.comEDIT : try it
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
sgminer.exe -k qubitcoin -o stratum+tcp://mine1.xbit.nonce-pool.com:4030 -u minerswing.1 -p 1 --no-submit-stale -I 18