Well if the player is working correctly, you can test for a problem is in the browser or embedding code. First try to download just the player by using the address found in your code here:
http://www.artistfactory.hu/mp3player/player.swf
Player direct download seems to work fine so it's probably in the way the browser is parsing the code. Taking a look at the source code shows one huge, glaring issue. The page has no DOC TYPE declared. Without that the browser will not know which set of rules to apply to the code on the page, which can result in a lot of wierd display problems.
Validate your page here:
http://www.w3schools.com/site/site_validate.asp
It will show you all errors and also provide a link to learn more about the need of a DOC TYPE on the page.
Start with that stuff anyway...
Best wishes,
Eye for Video
www.cidigitalmedia.com