I have Virgin wireless broadband, which works well until I start using gmail or skype video call. Suddenly the airport starts going off every few minutes. Downloading or streaming hasn't affected the internet connection, only this has. Is there anything to be done, please?

video chat uses a lot of your cable companies resources. You can't really be downloading songs and video chatting at the same time.

Try only video chatting. If that doesent work by itself then you should contact your cable company.

Actually you may want to try contacting them in the first place. Your airport shouild never turn off on its own. Typically the internet will just start getting very laggy. Are you talking about the airport on your macbook? Or do you have the airport router?