It seems as though it is confined to the Zergpool Pool at this time. I let it run overnight with Zergpool disabled and didn't have any issues. I enabled Zergpool this morning and right away I had a couple GPUs switch to Zergpool after a few minutes they switched to a different algorithm on Zergpool and stopped mining. I disabled Zergpool again, and all is working fine. So, it seems Zergpool isn't working too well for me.
I will test that pool as soon as I can to see if I can reproduce the issue. Aside from communication errors, I am not sure what the issue might be as the only difference to the software is the pools stratum server url. I am currently testing a fix for disabling specific algorithms on MiningPoolHub. If any adjustments are needed for Zergpool, Ill include them with that fix in 1.9.1
To follow-up, I switched more of my rigs to mine on Zergpool earlier today, both with the auto-switch ports as well as individual coins using the MC parameter. I haven't run into any errors mining so far, so you may want to try mining on that pool again to see if you connect this time. The attack on Verge last night caused a lot of issues with a lot of pools, so they have had some issues on the their end. If you see the issue again, please try copy and paste the exact error message so I can better troubleshoot the issue.
Version 1.9.1 fixes the issue with not being able to disable specific algorithms on MiningPoolHub. After you upgrade, you should be able to disable everything but Equihash on that pool if that is still your intent.