There is a race condition in the initscripts. /etc/init.d/initswitch first starts openvpn, then in /etc/init.d/startvpn starts openvpn agian. They conflict with each other. Disabling the switch masks the problem.
For more info see: VPN Instability getting old - #5 by nopro404
In that post I list a few lines you can add to the startvpn script to get the switch to work again.