hoping someone will be able to help with a problem on my wifes laptop.please be gentle as my knowledge of computing is very poor,acer extensa 5235,originally had an academic program installed,took it to a so called laptop expert (ha ha)he said he had re installed windows 7 (previous copy was locked) she has had it back about 3 months and now decides to tell me its faulty,every day a balloon appears saying low disk space,i clicked on my computer and its showing a guage by disk d this guage is red and its nearly filled the bar,she doesnt have a windows 7 disk so is there anything i can do.