When you say "rust", what colour is it? If it's a white powder then it's aluminium oxide which is the corrosion product of aluminium. Like Shaun says, the seal has failed and the whole unit needs to be replaced.
J
April 2008
thanks shaun supposed to be someone from company who installed windows coming AGAIN on monday ,just wanted to get some facts .one window clearly has condensation in between glass but a lot of the others looks like rust on aluminium in between
anne lees
April 2008
it should not rust because it is made of aluminium,it may have discoloured because there is moisture in your double glazed unit caused by the unit to have broke down,the only way to rectify this problem is to change double glazed unit.hope this helps
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix windows and doors.