Using WMC 7 via MediaBrowser - any time I fire up an MKV file about 2 minutes into the file it stutters for about 5 seconds and then straightens out and is fine for the duration of the video (it happens with all the mkv files I have(25)). Audio is output via spdif to receiver and video via HDMI straight to tv. The only Codecs installed are Lav and MadFlac for my music files. I read a post stating to chech that only 2 speaker setup is chosen but in wmc 7 the speaker setup only gives me the option for 5.1 or 7.1, so it is currently set at 5.1. Any advice?