I had the same problem with my iPad 1 a couple months back. A very helpful community member told me to do a hard reboot (continually hold the "Home" button - the round one with the white square on the front of the iPad - and the "Sleep/Wake" button on the edge of the iPad opposite the speaker) until the screen goes black and the silver apple apprears and the unit reboots (hold right through the screen with the red "Shut Down" slide on it). Take a look at your manual if you have trouble locating these buttons. That seems to have fixed my wi-fi problem for a few months. Problem... this newest "upgrade" brough back the wi-fi problem. I'm hoping the "forget" drill fixes this.
Amazing to me is that Apple, with all of it's resources, can't fix this problem once and for all. They have turned what was once a productive business tool into a toy. Hacks me off...