Address family not supported by protocol in Web-Proxy

Hello Dear Sirs. When I access web pages i randomly get “Address family not supported by protocol” error message by Web Proxy. I have only these rules enabled, but non of them are hit when I experience this error.


/ip proxy
set enabled=yes max-cache-size=none

/ip proxy access
add action=deny path=*.flv
add action=deny path=*.swf
add action=deny path=*.3gp
add action=deny path=*.wmv
add action=deny path=*.avi
add action=deny path=*.mp4
add action=deny path=*.mp3

/ip firewall nat
add action=redirect chain=dstnat comment=PROXY dst-port=80 protocol=tcp src-address=192.168.0.0/24 to-ports=8080

Also I have noticed that web pages sometimes are not fully loaded or content is diplayed improperly. I have tried to disable RAM cache, but this also did not help.

max-cache-size: none
max-cache-object-size: 2048KiB
cache-on-disk: no

CPU Load is around 2-5%

My RB2011iL - 6.30.2

Any ideas? Thank You in advance for help.