I`m using Windows 7 (x64), I have the Lacie Lacinema Classic HD media player (1TB) connected to a hard-wired ethernet connection and I`m using Twonky Media Server v5.1.3, also using version 220.127.116.11 of Eset Smart Security. I have been able to stream high definition .avi files without any issues at all. Yesterday, was the first time I attempted to stream a high definition .mkv file. The result was (after displaying the netwok files and selecting the said file) a blank TV screen. After returnng to the PC, I discovered the Lacinema_HD network icon gone from Windows7. Switched PC off and back on again..... still no icon. Applied a system restore to a few hours back and the icon appears again. Tried one more time and the same thing happened again. I then turned the firewall off in ESET SMART SECURITY and still nothing, so I uninstalled ESET completely and it reappears. At this point with no ESET installed I attempt to play the file again and it plays fine without any problems. So the conclusion is:- ESET DOESN`T LIKE .MKV FILES - BUT IT LIKES .AVI FILES. I then reinstall ESET and decide to investigate further.... looking at the firewall log in my AV software, on trying to play a .mkv file, I notice the log: DETECTED TCP FLOODING ATTACK 192.168.2.3.4497 DETECTED TCP FLOODING ATTACK 192.168.2.3.4105 DETECTED TCP FLOODING ATTACK 192.168.2.3.48547 Not really sure how this forum may be able to help me, I have contacted ESET over the issue..... I just wondered if anyone else has had similar problems with streaming high definition .mkv files with ESS? A friend of mine has exactly the same model as mine and uses McAfee AV software with Windows7 x64 and has no problem streaming high definition .mkv files via the same hard-wired ethernet method. Thanks in advance.