I'm not familiar with Kindle but you've tried the logical things, I assume including turning off wireless security altogether ?
Sounds like a call to Amazon to see if they have any thoughts.
hi have got this problem fixed after 4 days of net searches and late nights
first you need to install the latest up date
next you need to rename your wireless network to a name of 10 or less letters and spaces
next either no password or a password of 8 letters
all this got my kindle wireless working with aol broadband and a netgear adsl2+ modem router dg834g va also fully updated
dont you just love tech