White mould on house plant compost - help?

[Iffy]

Our house plants quite often get a sort of white mould growing on the surface of the compost. I've recently just planted a cutting of ivy in fresh compost, but this is still happening!

It doen't seem to matter whether the plants in the compost are old/new in light or dark, warmth or cold, it just seems to occur randomly, but I don't know what is causing it ? Also none of the plants are near others from which they may be "contaminated".

Can anyone help or give me ideas as to what it may be and does it harm the plants in any way?

[Aaldtimer]

Get some Cheshunt Coumpound from the garden centre and follow the instructions on the tin!