Dell 1558 wireless radio shuts self off

I've had my Studio 1558 laptop since about May. It has an Intel Advanced -N 6250 wireless card. I've had a problem where the wireless radio will periodically shut itself off. It's been doing this since the first weeks I've had the computer and seems to be getting more frequent (at least once every 2-3 hours). I can sometimes turn the radio back on with the F2 button, but lately this isn't working so well, particularly if its the 2nd or 3rd time the wireless radio has shut itself off during a session, and I usually have to reboot the whole system.  Has anyone else had this problem, and is there some kind of  a fix? This is really frustrating considering my ancient 8 year old Inspiron laptop never had this issue with its creaky first generation wireless card.