Does not working win NHML 1.8.1.10. The miner is starting, but did not working, no shares etc. After some times it is restarting.
Screenshot please. Also pay attention to starting difficulty of nicehash server - for me it was 8192, with this kind of diff it's hard to find even 1 share for several minutes if you don't have powerful rigs with many GPUs.
As for restart - NHML kills and restart miner for some reason, may be because it hasn't been able to find 1 share within some time period.