Zabbix Proxy not communicating with Windows Server

Interrupted system call - I've seen these in zabbix when connections are timed out. tcpdump is your best friend in this case. On the agent host, tcpdump -i any -n tcp port 10050 and see if you get incoming packets, if not, then there is something between the boxes or you don't have proper routing between the boxes or the host configuration in server has wrong IP. If instead you see incoming packets but not outgoing, then you do have a local firewall (iptables). Finally, if you see both incoming and outgoing, then you have to check on the server side if the response from agent gets there. If it does, then, finally, it is a strange situation.