rear window intermittent fault

hello i was wondering if anyone has had trouble with the electric rear windows on a disco mines a 96 nreg es ,
this has been bugging me for a bit now it seems that they only work after the vehicle is warm inside (i know it sounds daft but its true)
I saw a link about the window lift control panel under the dash having 2 desoldered joints , well ive had that out and they all look in tact , when the windows dont work the rear switches are inop aswell as the front controls for the rears , the front windows work spot on,
do you think it could be the switches or the window lift ?
when you put the front windows up you can see the dash display dim slightly , but the rears seem to have no power going to them when there inop thanks jon

CAN YOU HELP ME THANKS JON

you could have a dry joint on your control panel. which means that just because the soldered joints looks good it don't mean that it is good. so i would resolder them, to be sure. or maybe you have a bad earth some where which would account for the dash dimming.
first off redo the joints then if that don't do the trick get a multi meter and find out if you have power reaching the windows