Thanks Slowpoke - that's confirmed what I thought was the most likely scenario i.e. the sound card. As you say, I have the cassette deck going into the line-in of the pc. I've checked again the playback and record controls and none are muted (and the volume is turned up) - so I think it must be that the soundcard supplied with this Dell pc doesn't provide for hearing the sound when recording - altho', as I say, it records and then plays back fine.