Faced a problem. The miner just stops working. It does not hang and can be closed.
Same here.
Mining for 4 days and than in 7 AM just stop, when I came home about 6 PM just click to miner "h" or something, and miner start mining again

[2018-12-03 07:15:45] Pool at02.supportxmr.com share accepted. (GPU0) (a:12435 r:0) (36 ms)
[2018-12-03 07:16:06] Stats Uptime: 4 days, 07:15:55
[2018-12-03 18:55:49] Pool at02.supportxmr.com received new job. (job_id: fys23FOZGVBTDnniqeH7zmyUc6fW)
[2018-12-03 18:55:49] Pool at02.supportxmr.com set difficulty to 204697

SupportXMR pool show no hashing for that whole time.
So, I think we have new bug on 0.3.8

You might possibly have clicked into the miner with your mouse, leaving the cursor there and blocking it from working (known issue). If you press a key or click the cursor away mining resumes.
You can lock your window and prevent this from happening if you right-click on the top bar, then "properties" and uncheck "quick edit mode".