The possible causes of this issue are the following:
1) You are trying to play audio with audio format that our player do not support and you do not have any proper audio decoder installed on your machine(for example fro AC3 audio format you should have AC3 filter installed on your machine).
2) If you have installed all necessary codecs on your machine(AC3 filter for AC3 audio format) and the problems still repeats try to add proper decoder to the 'white filter list' of the player(Settings->Filters->White list) Elecard MPEG Player sometimes do not use AC3 filter installed on machine, this issue will be fixed in the next version 5.6 that we expect in the next month.
Should you have further questions please do not hesitate to contact our technical support department via email:
tsup@elecard.ru