I've had hesitant el front windows in my 9000 for quite some time. They usually don't work immediately, but seems to come to life later into a journey. I usually inspect the fuse, but it is always OK. I suspected the switches, but the problem is very simple; it's just oxidation on the 30 amp fuse. The fuse is probably 10 years old like the car and a high current is required, so any oxidation blocks the current. That is why the windows always seem to work after I've checked the fuse, but I never thought of the oxidation :-)