Post 9.104-17, web proxy hangs randomly, error in log "tunnel_handler_recv_data"

Hello,

Since our UTM625 was upgraded to 9.104-17, we've seen periods of ...hanging...while using the web proxy. It's completely random but as the load increases it occurs more often.

We're seeing the following errors in our http.log:

2013:08:21-00:04:21 xo-mn-dc-1 httpproxy[6528]: id="0003" severity="info" sys="SecureWeb" sub="http" request="0xdf273e60" function="tunnel_handler_recv_data" file="tunnel.c" line="45" message="epoll_fill_buffer: Connection reset by peer"
2013:08:21-00:04:38 xo-mn-dc-1 httpproxy[6528]: id="0003" severity="info" sys="SecureWeb" sub="http" request="0xda39fdc0" function="tunnel_handler_recv_data" file="tunnel.c" line="45" message="epoll_fill_buffer: Connection refused"
2013:08:21-00:07:14 xo-mn-dc-1 httpproxy[6528]: id="0003" severity="info" sys="SecureWeb" sub="http" request="0xdc956378" function="tunnel_handler_recv_data" file="tunnel.c" line="45" message="epoll_fill_buffer: No route to host"

Now, I don't know if these errors are related but I'm at a loss at where else to look. Since midnight, there are 9500 entries in the http log containing those errors.

What else should I be looking at to help source the ... hangs .... ? It is very noticeable when it occurs.

Any suggestions on other log files to examine / processes to maybe turn off (AV? Caching?). This started with the upgrade as I mentioned. Prior to, this did not occur. CPU/Mem usage is 3% / 20% respectively.

Thank you
David