Exactly the same problem as described here. I too had left it mostly alone for some months, only occasionally using it and not at home. It always worked fine, but at home, where it used to work with no problem, now it is quite difficult to get a connection. This is with the two versions I have installed, sorry it was so long ago I forget what is on there. I have not installed the wifi bugfix and am downloading the latest full OS that fixes that.

EDIT1: After posting the above I flashed 2008HE onto my 770 and have the same problem. Later today I'll add the MMC boot and also try at a location I know worked just a week or two ago. But I'm becoming convinced it's a problem with -n wifi signals. That seems to be the common factor with my setup and others'.

EDIT2: It connects perfectly in the location that doesn't have any -n wifi routers around.