Hello, I´m currently in China too and experienced exactly the same problems with Secure Line since December 2014.
I also suspected either windows update problems or the Great Firewall causing the problems.
So I wrote “tickets” to the AVAST support but they did long time not reply on the issue. Then they told me to reinstall Avast which I did and Internet Security works but Secure Line doesn´t handle the Licence even though it is recognized as valid by Avast in the first step. That Secure Line has problems caused by the Great Firewall is understandable, but what makes me mad is that AVAST support does not react on my written “tickets”. Espeacially since I have purchaised for 2 years in total. Not knowing how to solve the problem is no shame but not answering at all really is not acceptable. So better find another VPN service.