Work only under private proxy but it work without proxy sometimes

I have a problem – I work only through a privat proxys, but sometimes GSA simply loses sight of this option and I catch a lot abuses on my server. GSA can work well 10-20 hours and in no reason for few hours just switch off  use proxies and i got 100-200 abuses for this time, and after that GSA again work well.
I got this few times in a month
What should I do?