Yep, classic problem mate. Mine are sometimes like this, I find that putting a small amount of pressure on the glass and helping them back up works ok. If you find them going really slow, this means they are taking all the charge outta your battery, leccy windows take a lot of power to go up and down, but the main cause would probably be the electric window motors are knackered, mine does it too, but I'm not too fussed about it at the mo, I think most RST's do it tbh.