Testing 2.8.6 on Win7 x64.
There are lots of messages "Accepted untracked stratum share" among regular "Accepted 68132465..." ones.
What do they mean?
p.s. It took about 50 sec to recover normal operations when I switched to another wifi network.
And it died when I switched back.
That means the stratum pool you are mining with is returning "accepted" messages without the same ID that cgminer sent the share with, so cgminer doesn't know which shares the pool is accepting. The communication is all done asynchronously and cgminer keeps a database of sent shares so that when it gets a response from the pool it can tell you which share it was.