Troubleshooting SKYPE on a Packard Bell computer

[Ritz]

I live in the USA. My rellie in the UK is a senior citizen who is trying to communicate with me via SKYPE. He keeps getting a message box saying 'problem with playback device.' He is using Windows XP, but I'm not sure of his Packard-Bell computer model or its age. For awhile, I could see his live image on the Skype screen, but I could not hear him. Now, he's having difficulty getting through at all.

Can someone advise? Thank you.