more than likely it will be the frames dripping down or the rubbers leaching all the fairy and muck that sits under them.
if its the frame dripping easy to sort, clean it till there is no dirty water running down, then lift off brush and direct a jet all across the top. clean the glass, then move on to the next one (if first clean) do the same, on all the top windows then go back and do the glass only.
if it's the rubber seals, then like nwh said, it really can take months till they come right(perfect), they will still look cleaner but not perfect sometimes. or a good scrub with lots of water and they look great.
another way is to clean frame and glass all way round, then wait till they start drying off, (easier on hot days) if any runs, then just give a rinse.