Condensation?

In the winter we run our houses warmer - warm air can carry more moisture than cold air - when the warm air meets a cold surface it cools and water is squeezed out - condensation,

Your solutions are:
Wipe up the damp as soon as you see it - stops mould growth
Insulate the windows with curtains or blinds to form a barrier if you can
Ventilate the house a little more
Reduce the heating if you can - even a bit - save money
Keep bathroom and kitchen windows open when creating steam - even in the coldest weather just a bit open - and keep the doors closed.
Consider a dehumidifier - mine cost £160 and can easily suck a litre of water from the air in a day!

Condensation is a modern curse brought about by the combination of Central Heating, Double Glazing and no natural ventilation - older houses tend to suffer less because they're more draughty.

http://www.scotland.gov.uk/Publications/2005/05/10103020/30217

Good luck...

Peccavi
December 2009