Bizarre windows

[magnum80]

Had a bit of a problem with my WS Zetec lately, when I try and put the drivers side window up it reaches the top then drops down to about 3/4 open and keeps doing this. however if I put it all the way down and put it back up again it closes but wont go up automatically, have to hold the switch.
Anyone else had this problem or know whats causing it? Have my 15000km service up in a few weeks so will get them to look at it if it doesnt right itself