avi and mkv videos in Sony KDL-46HX820 (BRAVIA)

[Illico]

Do you have fixed ip addresses on the PCs?

How do I find out?

Solution(1)
On windows 7 task bar, near clock, right click on "network icon" -> Open Network and sharing center -> Change adapter settings -> properties on your network NIC -> properties on IPV4 Protocol (IPV6 protocol could be disabled) -> Use a specific ipaddress:
IP address : 192.168.1.X ( ex: 192.168.1.10, 192.168.1.11, etc)
Submask : 255.255.255.0
Default gateway : 192.168.1.1 (should be your router ip address)
Preferred DNS server : 192.168.1.1 (router IP address)

Solution(2):
On router settings, fix device IP address according to there MAC address