In order to fix the issue, go to Start, type dxdiag and open the application. Click the Sound tab, check your sound card model and navigate to the developer web page and download and install the latest drivers available. If it still doesn't work, try opening the file with other program from Software Informer database. If it doesn't work, it means the file you want to play is corrupted. If it works, uninstall Real Player and download and install the latest version from the official web page.
